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Bomb Threats in Schools

Guide No. 32 (2005)

by Graeme R. Newman

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The Problem of Bomb Threats in Schools

What This Guide Does and Does Not Cover

The guide begins by describing the problem and reviewing factors that increase the risk of bomb threats in schools. The guide then identifies a series of questions that might assist you in analyzing the local problem of bomb threats in schools. Finally, the guide reviews responses to the problem and what is known about these from evaluative research and police practice.

The scope of this guide is limited to bomb threats in schools, public or private, kindergarten through 12 th grade. Colleges and universities are excluded because they generally differ from schools. Their organization and administration differ; they have their own police within the university community; and many universities do not have a physically identifiable perimeter as schools do. In fact, college campuses have much more in common with other public service organizations, such as health services, entertainment venues and, to some extent, shopping malls. While there are a number of common responses to bomb threats that apply to almost any setting, the environment of schools is sufficiently different to warrant separate consideration.

The feature that distinguishes a bomb threat from other kinds of assaults and threats is that it is primarily a furtive crime—or at least a crime that can be committed from a distance. Modern communications make it possible for offenders to communicate their threat without having to physically confront the targets at the time of the threat or even at the time of the assault. Many assaults or destructive acts in schools follow threats, or constitute threats in themselves. The reason why an offender might choose a bomb as the carrier of the threat over some other item or implement of destruction and injury (e.g., assault weapons, arson) is unknown, though the immediate, disruptive action it causes is surely part of the reason. Certain kinds of injury and damage may also be enhanced by a bombing, such as arson achieved through an explosive device.

Related Problems

There are several problems related to bombs, threats, and schools that are not directly addressed in this guide and merit separate analysis. They include:

  • Assaults on school officials
  • Bomb threats that occur in other locations and against targets other than schools (e.g., businesses and other workplace environments, public spaces such as shopping malls, public event venues such as entertainment and spectator sports, transportation, health services, government services)
  • Bullying in schools
  • Burglaries of schools
  • Carrying weapons in schools
  • Drug dealing in and around schools
  • False fire alarms†
  • Gang violence
  • Graffiti at schools
  • Hate crimes
  • Hazing
  • School pranks that cause disruption
  • Shootings
  • Sport violence (where team spirit is taken to an extreme)
  • Stalking (either of students or by students against teachers)
  • Threats to harm teachers or students, including death threats
  • Vandalism of school property.

† See the POP Guides on False Alarms and Misuse and Abuse of 911.

Extent of Bomb Incidents and Bomb Threats

Data on bomb incidents (any event in which an actual bomb or bomb look-alike is involved) and bomb threats (any event in which a bomb threat is communicated that may or may not involve an actual bomb or bomb look-alike) are limited. The FBI reports that close to 5 percent of bombing incidents in the United States in 1999 (the most recent year for which FBI data are available) were targeted at schools. It is unknown what portion of these incidents involved threats. For the period January 1990 to February 28, 2002 the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) recorded 1,055 incidents of bombs being placed in school premises.1 Again, we do not know what proportion of these incidents involved threats. For the most part, however, it is probably reasonable to conclude that bomb incidents involving real bombs in schools are relatively rare, though they have been with us for quite some time.‡ Furthermore, relatively few bomb explosions are preceded by a warning or threat to officials. Of the 1,055 bomb incidents in schools reported by ATF, only 14 were accompanied by a warning to school or other authorities.

‡ The first known school bombing occurred in May 1927 in Bath, Michigan. A local farmer blew up the school, killing 38 pupils, six adults and seriously injuring 40 other students ( Missouri Center for Safe Schools 2001).[Full text ]

There are no national statistics on bomb threats as such, though they are more common than bomb incidents. However, we can say that they are not evenly distributed throughout school districts: rashes of bomb threats can occur in particular localities.2 For example, in the 1997-8 school year, one Maryland school district reported 150 bomb threats and 55 associated arrests.3 The South Carolina Department of Education in its 1999-2000 school incident crime report lists "disturbing schools," which includes bomb threats, hoaxes, false fire alarms etc., among its 10 top crimes, second only to simple assaults.4 During the past five years, many states have enacted severe penalties for issuing false bomb threats, which reflects the perception that the incidence of bomb threats is widespread.

Impact on Victims

The occurrence of bomb incidents or threats can have a major impact on the targeted victims depending on how the school responds. The potential for serious injury and damage makes even an empty threat a very serious incident. Thus, even though some 90 percent of bomb threats in schools may turn out to be pranks,† each threat must be taken seriously and acted upon immediately. Evacuation of buildings causes major disruption, which in many cases may be an attractive outcome from the offender's point of view. Many school districts report losses in excess of $250,000 because of school closings and costs of bomb search squads. School districts are increasingly requiring schools to make up days lost due to bomb threats.5

† This is a widely quoted statistic. To the extent that the author could determine, it is not based on any specific research study. The Hartford Insurance Company (Hartford Loss Control Department 2002) reports that 5 to 10 percent of bomb threats involve real bombs. See http://mb.thehartford.com/insurance_info/pdfs/570-050.pdf.

Finally, the publicity that surrounds rare but shocking incidents of targeted violence in schools affects all communities, even those far away from where the incidents occur. After the Columbine incident,‡ more than 70 percent of respondents nationally said that the same thing could happen in their community. Fear of targeted violence in schools far outstrips the actual risk,§ which makes responding to threats extremely difficult for school authorities that may be hesitant to reveal the occurrence of every single bomb threat that occurs, particularly if there is strong indication that the threat is false.

‡ The Columbine High School massacre occurred on April 20, 1999, in Jefferson County, near Littleton, Colorado. Two teenage students planned the massacre, carried it out by shooting 12 students and one teacher, and committed suicide.

§ According to Reddy et al. (2001) "the three major television networks: ABC, CBS, and NBC, aired a total of 296 stories on the shooting at Columbine High School in Jefferson County, Colorado…in contrast, lightning accounts for more deaths overall, and bathtub accidents account for more deaths of children, than do school shootings…yet, they receive comparatively little media coverage."

About Bomb Threats

Motives: There are many supposed motives for bomb threats, among them: humor, self assertion, anger, manipulation, aggression, hate and devaluation, omnipotence, fantasy, psychotic distortion, ideology, retaliation and no doubt there are many more.6 However, the research on motives is generally limited to other kinds of violence, so any imputation of motives to those who deliver bomb threats must remain speculative.

Delivery: Bomb threats are delivered in various ways: by letter, face-to-face, e-mail, on a student's website, or even a gesture. However the most common means of delivering a bomb threat is by telephone.7

How seriously should a threat be taken? The seriousness of a bomb threat is self evident because of the potential for widespread destruction that can be wrought by a bomb, compared to other weapons that are usually aimed at particular targets. However, if, as we have noted already, 90 percent of bomb threats are hoaxes (either there is no bomb at all or the "bomb" is a fake), how seriously should the threat be taken? Since the extent of disruption caused by bomb threats is considerable whether the bomb is real or not, all such threats are often responded to on the assumption that a real bomb does exist. In fact, the law throughout the United States tends to treat false bomb threats almost as severely as real bomb threats† and makes little exception for juveniles. Yet in the hurly-burly of the school setting, many threats are made in the normal course of the day among students and between teachers and students, some of which allude to explosives. The majority of such threats are never reported to the police. For example, a student states to his gym teacher, "All jocks deserve to be blown up." The seriousness with which to take this threat depends on how it is delivered. If the student was laughing or joking, the teacher may pay no mind to it. If made by a student with a history of such pronouncements, the threat may be taken more seriously. It is therefore important for schools to develop a response plan that includes criteria for making assessments of seriousness and for adopting responses commensurate with that assessment (see below).

† Making a false bomb threat is a federal offense punishable under United States Code 18-844(e), with a penalty of up to 10 years in prison, $250,000 fine, or both. This penalty also applies to juvenile offenders (Bureau of Alcohol, Tobacco, Firearms and Explosives 2003). However the majority of juveniles are prosecuted under local and state laws, which increasingly provide severe penalties.

Specificity of Bomb Threats. In general, the specificity of the bomb threat is the best guide to its seriousness.8, ‡ The specificity of a bomb threat may be assessed according to:

‡ This is a widely held view among experts. There is, however, no formal research study that affirms or negates it.

  • Place and time indicated in the threat
  • Description of the bomb to be used
  • Specific targets mentioned or indicated
  • Reason given or implied in the threat.

Table 1 summarizes in a general way the reasons given or inferred for issuing bomb threats and their links to the specificity of the threat. This is a classification based on information published in newsletters and other information outlets of government and non-government organizations that typically respond to bomb threats. Certain kinds of bomb threats are likely to be more specific than others. For example, a conditional threat must state the condition to be met, which requires much more specificity. In general, the more specific the threat, the easier it is to decide on the response.

Table 1: Types of bomb threats in schools and their specificity

TypeThreat rationaleVague threatSpecific threat
Conditional"Do this or else.""Put back the candy machines or Ill bomb the school." Student expressing outrage, probably no bomb unless there has been a series of such threats."If you dont put back the vending machines, a bomb will go off in the cafeteria at 12 o'clock today."
InstrumentalThreat made in order to achieve another usually immediate goal.Offender calls school and says, "There's a bomb in the building" and immediately hangs up. Student calls in false bomb threat in order to disrupt classes and get the day off."I've put a bomb in the school set to go off at 10:00. Burn down the school!"
Getting evenBomber inverts power relationship between himself and the target."Death to all and I shall rule the world." Student places this threat on his website. Threat does not explicitly mention bomb. If identity of threatener is known should probably be taken seriously, especially if past history of threats."I'm sick of being humiliated by Smith. Today is the day when Smith and his precious science labs will be terminated."
Hate (ideological, religious, ethnic)Bomber makes threat against hated opponent or target."Death to all child murderers!" Threat called into a school day before family planning officials visit school."Stay away from school tomorrow. The child murderers will be blown to hell where they belong! I'm not joking!"

Highly specific bomb threats tend to be more credible. Photo credit: David Corbett

Factors Contributing to Bomb Threats in Schools

Understanding the factors that contribute to your problem will help you frame your own local analysis questions, determine good effectiveness measures, recognize key intervention points, and select appropriate responses. Unfortunately, there is no research that directly addresses the causes of bomb threats in schools. There is, however, a limited amount of research that examines how threats of various kinds arise in schools and the situations in which they occur.9 The majority of this research is directed at developing two types of response: (1) an intervention plan aimed at prevention of threats and reducing their harm if carried out and (2) a response protocol in the event that an actual bomb threat or incident occurs. All of the research on which these two responses are based is focused on threat assessment, a protocol developed by the U. S. Secret Service to identify in advance individuals who may be most likely to attack the President and other individuals the Secret Service is responsible for protecting.

The methodology used in these studies has been to collect detailed information concerning the circumstances that prevailed before and after major cases of targeted violence, including shootings and bombings. This information is then analyzed for any patterns that may indicate those circumstances that seemed to be conducive to targeted violence. The Secret Service applied this methodology to 37 cases of targeted violence in schools (which included some bomb-related events), collecting data on the personal and background characteristics of the offenders, their behavior before the violence occurred, and the school administrative and interpersonal response to the behaviors of the offenders before and after the event.

Based on the results of the Secret Service studies and those of student surveys,10 there are four factors that contribute to bomb threats in schools and these factors interact in different ways in different situations:†

† "There is no profile or single 'type' of perpetrator of targeted violence. Rather, violence is seen as the product of an interaction among the perpetrator, situation, target, and the setting" (Reddy et al. 2001).


The Secret Service study of incidents of targeted violence in schools concluded the following:11

  • The attacks were rarely impulsive; 75 percent planned the attack.
  • The attacks were the end result of a series of events that to the attacker seemed logical and inevitable.
  • Often the planning of the attack consumed almost all the attacker's time and energy to the point of obsession.
  • Most held a grievance at the time of the attack.
  • Most of the attackers had actually told a peer that "something would happen."

‡ The Secret Service study found that "In virtually all…cases, the attacker told a peer. In only two of 37 cases did the peer notify an adult" (Vossekuil et al. 2002). [Full text ]

  • There was no definitive "profile" of an attacker, though there were many warning signs (Appendix B) that could possibly prove useful in identifying possible attackers.

While there has been some suggestion that bombers have particular types of personalities (obsessive-compulsive, psychopathic), there is insufficient scientific evidence to back up this claim.12 Finally, the vast majority of threats are called in by students, though there are occasional cases of threats by teachers.§

§ A third-year middle school mathematics teacher who reportedly told police she wanted the day off was charged Tuesday with calling in a bomb threat to Grayling Middle School ( Traverse City Record Eagle, April 10, 2002).

Family Background

No research has definitively, or even roughly, identified a constellation of factors that causes an individual to issue a bomb threat or target violence in a school. However, the general literature of law enforcement and school authorities (e.g., FBI, U.S. Secret Service, ATF working with the Department of Education) has identified a number of possible factors, though it should be emphasized that this does not mean that any one or even several of these factors necessarily lead to bomb-threatening behavior:13

  • History of violence in the home
  • Parental acceptance of pathological behavior
  • Careless use of weapons in the home by parents, easy access to weapons, use of threats of violence to solve disagreements
  • Family moves frequently
  • Lack of intimacy in the home
  • Parents set no limits on child's conduct
  • Excessive watching of TV, violent video games allowed
  • No monitoring of outside interests, including drug and alcohol use, gang activity.


A school climate that is insensitive to provocations to violence (such as bullying, harassment by teachers and students, an excessively authoritarian climate,† lack of respect of students for each other or teachers, gang activity, presence of provocative graffiti, lax dress rules, etc.) may be more likely to be a target of bomb threats. And where a school lacks basic prevention programs against attackers (such as monitoring entry and exit to the school, surveillance of areas in the school where bombs may be left, training of teachers to deal with violence in schools, and a systematic program for identifying and reporting warning signs), it too may be more likely to receive bomb threats.

† Harsh imposition of authority by a school that relies entirely on fear not only has been associated with violence against teachers but also may result in a students unwillingness to come forward to communicate potential problems of violence including his or her own victimization (Regoli and Hewitt 1994, Curcio and First 1993).


Making a bomb is easily within the ability of juveniles. In fact, ATF reports that the success rate of bomb detonations for bombs in schools is slightly higher than that for the national rate of all bombings. The range of explosive substances and ways of detonating them are limited only by the bomber's imagination and resourcefulness. Information on how to construct them is readily available on the Internet or is widely available in books.† Obviously, since this information is available to everyone should they wish to seek it out, its availability per se does not tell us which individuals are likely to make a bomb threat. Many of the recipes for making bombs use common everyday chemicals. However, even obtaining such information does not mean that individuals will use it to make a bomb or issue a bomb threat. Of course, they do not need any information on constructing bombs if they plan to issue a false bomb threat.

† There are many websites that provide the necessary information, though probably the most widely known is The Anarchist Cookbook of which there are many versions online (www.righto.com/anarchy/online.html) or the original is available in hard copy from many book stores. This book provides directions on everything from how to make letter bombs to counterfeiting currency. Another popular source is the Black Books of Improvised Munitions Handbooks, providing information on improvised explosives, bombs, firearms, timers, etc. This is a version of the U.S. Army Technical Manual 31-210.

Concealment is also not difficult. Although bombs may be concealed in an incredible variety of containers—from fire extinguishers to pens and letters—most bombs are of the simple pipe bomb form that is concealed in an ordinary-looking bag or some everyday object.14, § Letter bombs are extremely rare, though they receive considerable media coverage.‡

§ The typical Hollywood device is sticks of dynamite with a clock taped to it. In fact, the most common device is a pipe bomb, a length of pipe filled with explosive (Bureau of Alcohol, Tobacco, Firearms and Explosives 2003).

‡ The U.S. Postal Inspection Service reports that of 170 billion pieces of mail processed in a typical year, only a very few letter bombs—an average of 16—are reported or investigated (Hartford Loss Control Department 2002). [Full text]

hoax caller

Bomb threats have often been called in via pay phones which reduced the likelihood that police could locate the individual placing the call. Credit: David Corbett

Part of the means to carry out a bomb threat effectively is the placement of the bomb. The preferred places are in areas where there is constant public access.Of the 1,055 incidents reported by ATF, 92 were outside, many of these in the parking lot; 190 inside, the majority either in the restroom or in a locker; and 123 either inside or outside in trash cans, air conditioners, window or door areas.15 The opportunity to place a concealed bomb without detection is considerable unless the school has an established system of monitoring its premises.

Finally, the telephone's popularity for delivery of threats hardly needs explanation: it is widely available, cheap, and provides a (perhaps) false sense of anonymity for the caller. Pay phones exist in many if not all schools, and cell phones—until recently difficult to trace—are widely available among students. As we will see below, monitoring this ready-made threat delivery system may be one useful preventive response.

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