By Mary Ellen O'Toole

This paper presents a systematic procedure for threat assessment and intervention of school shooters. The model is designed to be used by educators, mental-health professionals, and law-enforcement agencies and is intended to help refine and strengthen the efforts of the National Center for the Analysis of Violent Crime. Its fundamental building blocks are its threat-assessment standards, which provide a framework for evaluating a spoken, written, and symbolic threat, along with a four-pronged assessment approach, which looks at the personality of the student, the student's family dynamics, the school dynamics, the student's role in those dynamics, and social dynamics. The model is not a profile of the school shooter or a checklist of danger signs pointing to the next adolescent who will bring lethal violence to a school. It discusses misinformation about school shootings; how to assess a threat, including motivations; types of threats; factors in threat assessment; and levels of risk. The document cautions that one or two traits or characteristics should not be considered in isolation or given more weight than the others. The text outlines the intervention process and closes with a number of recommendations. Four appendices list methodologies used in the report, suggested readings, and other information. (RJM)

Quantico, VA: Critical Incident Response Group (CIRG), National Center for the Analysis of Violent Crime (NCAVC), FBI Academy , 1999. 52p.

By Edward Gaughan, Jay D. Cerio, and Robert A. Myers

American public schools are safe places, perhaps even safer than American homes. The tragic school shootings that are the focus of this report have occurred in less than one-hundredth of one percent of schools. The probability of being shot at school is similarly low. But shootings have occurred at schools, have been largely unpredictable, and have raised the anxieties and concerns of students, families, teachers, and the public at large. Between 1974 and 2000, the National Threat Assessment Center (NTAC) of the United States Secret Service identified 37 incidents. At least 20 incidents have been reported in the national media since 1992, and eight since 1999, and these do not include several planned shootings that were prevented by authorities. Why do these shootings occur? Why do they occur where they do? What can we do to protect our children?

Alfred, NY: Alfred University, 2001. 44p.

By J,M, Nowicki

GAO found that shootings at K-12 schools most commonly resulted from disputes or grievances, for example, between students or staff, or between gangs, although the specific characteristics of school shootings over the past 10 years varied widely, according to GAO’s analysis of the Naval Postgraduate School’s K-12 School Shooting Database. (See figure.) After disputes and grievances, accidental shootings were most common, followed closely by school-targeted shootings, such as those in Parkland, Florida and Santa Fe, Texas.

Washington, DC: Government Accountability Office, 2020. 58p.

By Jay Van Kirk

Mass shootings occur on a regular basis in the United States, and depending on the definitions applied to the shootings an argument can be made that mass shootings of all types occur far more often than what is reported in the media as a “mass shooting.” Unfortunately, school shootings are also part of this analysis of mass shootings, and school shootings in the United States have occurred on a recurring basis since at least 1853. In the modern era, however, school shootings have become more frequent and more deadly as demonstrated by the May 24th, 2022, school shooting in Uvalde, Texas. This heinous crime at Robb Elementary School resulted in the deaths of nineteen children, and two teachers. Although there has been extensive research on mass shooters, mass shootings, and mass shootings in schools, there has not been enough emphasis on the application of homeland javascript:void(0);security principles of target hardening in schools as a risk mitigation factor for mass shootings. In fact, there is much that can be done to keep schools safe through basic target hardening measures, and many of these security updates can be immediately undertaken at the state and local level with relatively minor additional cost to schools and the taxpaying public. This paper references the mass shooting on February 14, 2018, at Marjory Stoneman Douglas High School in Parkland, Florida, and makes policy recommendations toward basic target hardening measures which may be applied as necessary within the public school K-12 environment. The school shooting at Marjory Stoneman Douglas High School was selected due to the fact that it has been recently investigated regarding the facts and circumstances of the incident, and provides ample information for analysis of effective target hardening measures.

Des Moines, IA: Des Moines Area Community College, 2022. 17p.

By William Krouse and Daniel J. Richardson

In the wake of tragedy in Newtown CT, Congress defined “mass killings” as “3 or more killings in a single incident” (P.L. 112-265). Any consideration of new or existing gun laws that follows mass shootings is likely to generate requests for comprehensive data on the prevalence and deadliness of these incidents. Despite the pathos of mass shootings, only a handful of researchers and journalists have analyzed the principal source of homicide data in the United States—the Supplementary Homicide Reports (SHR) compiled by the Federal Bureau of Investigation (FBI)—to determine whether those incidents have become more prevalent and deadly. According to the FBI, the term “mass murder” has been defined generally as a multiple homicide incident in which four or more victims are murdered, within one event, and in one or more locations in close geographical proximity. Based on this definition, for the purposes of this report, “mass shooting” is defined as a multiple homicide incident in which four or more victims are murdered with firearms, within one event, and in one or more locations in close proximity. Similarly, a “mass public shooting” is defined to mean a multiple homicide incident in which four or more victims are murdered with firearms, within one event, in at least one or more public locations, such as, a workplace, school, restaurant, house of worship, neighborhood, or other public setting. This report analyzes mass shootings for a 15-year period (1999-2013). CRS analysis of the FBI SHR dataset and other research indicates that offenders committed at least 317 mass shootings, murdered 1,554 victims, and nonfatally wounded another 441 victims entirely with firearms during that 15-year period. The prevalence of mass shooting incidents and victim counts fluctuated sporadically from year to year. For the period 2007-2013, the annual averages for both incidents and victim counts were slightly higher than the years from 1999-2007.

Washington, DC: Congressional Research Service, 2015. 51p.

Edited by Rajeev Ramchand, Jessica Saunders

This report, part of RAND's Gun Policy in America project, presents a collection of essays that synthesize the available scientific data on topics pertinent to firearm policy in the United States. In particular, the authors examine mass shootings, firearm and ammunition taxes, the effects of the 1996 National Firearms Agreement in Australia, whether mental illness is a risk factor for gun violence, and law enforcement approaches to reduce community gun violence.

Santa Monica, CA: RAND Corporation, 2021. 115p.

By Michael Luca, Deepak Malhotra. and Christopher Poliquin

There have been dozens of high-profile mass shootings in recent decades. This paper presents three main findings about the impact of mass shootings on gun policy. First, mass shootings evoke large policy responses. A single mass shooting leads to a 15% increase in the number of firearm bills introduced within a state in the year after a mass shooting. This effect increases with the extent of media coverage. Second, mass shootings account for a small portion of all gun deaths, but have an outsized influence relative to other homicides. Third, when looking at bills that were actually enacted into law, the impact of mass shootings depends on the party in power. The annual number of laws that loosen gun restrictions doubles in the year following a mass shooting in states with Republicancontrolled legislatures. We find no significant effect of mass shootings on laws enacted when there is a Democrat-controlled legislature, nor do we find a significant effect of mass shootings on the enactment of laws that tighten gun restrictions.

Boston, MA: Harvard Business School, 2019. 59p.

By Vivian S. Chu

As the Internet has become a significant venue for facilitating commercial transactions, concerns have arisen regarding the use of this medium to transfer firearms. This report discusses the sale of firearms and ammunition over the Internet, with a focus on the extent to which federal law regulates such activity. A review of the relevant factors indicates Internet-based firearm transactions are subject to the same regulatory scheme governing traditional firearm transactions. Over the years, this has raised concern about the possibility of increased violation of federal firearm laws, as well as challenges that law enforcement may face when attempting to investigate violations of these laws. A review of the relevant factors also indicates that the sale and transfer of ammunition are not as strictly regulated as firearms, and that these changes came into effect in 1986. Lastly, this report highlights recent legislative proposals, S. 3458 and H.R. 6241, companion measures introduced by Senator Frank Lautenberg and Representative Carolyn McCarthy in the 112th Congress that would affect online ammunition transactions.

Washington, DC: U.S. Library of Congress, Congressional Research Service, 2012. 11p.

By Joshua Horowitz and Casey Anderson.

When gun enthusiasts talk about constitutional liberties guaranteed by the Second Amendment, they are referring to freedom in a general sense, but they also have something more specific in mind---freedom from government oppression. They argue that the only way to keep federal authority in check is to arm individual citizens who can, if necessary, defend themselves from an aggressive government. In the past decade, this view of the proper relationship between government and individual rights and the insistence on a role for private violence in a democracy has been co-opted by the conservative movement. As a result, it has spread beyond extreme militia groups to influence state and national policy. In Guns, Democracy, and the Insurrectionist Idea, Joshua Horwitz and Casey Anderson set the record straight. They challenge the proposition that more guns equal more freedom and expose Insurrectionism as a true threat to freedom in the United States today.

Ann Arbor: University of Michigan Press, 2009. 287p.

By Ralph Larkin. 

On April 20, 1999, two Colorado teenagers went on a shooting rampage at Columbine High School. That day, Eric Harris and Dylan Klebold killed twelve fellow students and a teacher, as well as wounding twenty-four other people, before they killed themselves. Although there have been other books written about the tragedy, this is the first serious, impartial investigation into the cultural, environmental, and psychological causes of the massacre. Based on first-hand interviews and a thorough reading of the relevant literature, Ralph Larkin examines the numerous factors that led the two young men to plan and carry out their deed. Rather than simply looking at Columbine as a crucible for all school violence, Larkin places the tragedy in its proper context, and in doing so, examines its causes and meaning.

Philadelphia: Temple University Press, 2007. 265p.

By Steffen Hurka.

Politicization and Policy Change in Western Europe. While the causes of rampage violence have been analysed thoroughly in diverse academic disciplines, we hardly know anything about the factors that affect their consequences for public policy. This book addresses rampage shootings in Western Europe and their conditional impact on politicization and policy change in the area of gun control. The author sets out to unravel the factors that facilitate or impede the access of gun control to the political agenda in the wake of rampage shootings and analyses why some political debates lead to profound shifts of the policy status quo, while others peter out without any legislative reactions. In so doing, the book not only contributes to the theoretical literature on crisis-induced policy making, but also provides a wealth of case-study evidence on rampage shootings as empirical phenomena.

London; New York: Routledge, 2017. 201p.

By Michael R. Vernick, Jon S., Webster, Daniel W.. “The role of guns in violence, and what should be done, are subjects of intense debate in the United States and elsewhere. But certain facts are not debatable. More than 31,000 people died from gunshot wounds in the United States in 2010….Despite the huge daily impact of gun violence, most public discourse on gun policy is centered on mass shootings in public places. Such incidents are typically portrayed as random acts by severely mentally ill individuals which are impossible to predict or prevent.”

Bloomberg. Johns Hopkins Press (2013) 312p.