K-12 School Shootings in Context: New Findings from The American School Shooting Study (TASSS)

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August 23, 2023

Brent R. Klein
Joshua D. Freilich
Steven M. Chermak


Although statistically rare, fatal and nonfatal shootings in the United States at elementary, middle, and secondary schools remain important crime problems with significant public policy implications. Indeed, the impact of such violence exceeds the devastating fatalities and immense sorrow that survivors, families, and communities experience. Even one gunshot fired at a school can subject numerous individuals to the traumas of gun violence. Recent polls indicate that school shootings can also sway broader public views on crime, including attitudes toward violence reduction. As a result, school shootings have become a focal point of US politics, sparking crucial debates on the most effective strategies for preventing and responding to gun violence, both inside and outside K-12 schools.

While there has been a recent surge in school firearm violence studies, discrepancies persist in the research due to variations in definitions and datasets. Initially, our comprehension of school shootings originated from narrow studies focused on small samples of highly publicized mass killings where attackers indiscriminately fired upon multiple victims in their schools. By contrast, recent progress in quantitative studies and the establishment of extensive databases have provided alternative perspectives on the characteristics of school shootings more broadly. Within this domain, however, there are disparities in inclusion criteria, as some studies encompass school-related violence occurring both within and outside of school premises, leading to an inconsistent research base.

We created The American School Shooting Study (TASSS) in 2016 to address these incongruencies in the existing research. Previously, we reported findings from TASSS on the patterns and nature of US school-associated gun violence between 1990 and 2016, defined as the firing of a gun anywhere on K-12 school property, resulting in one or more gunshot injuries or fatalities, irrespective of the time of day or season. Our findings suggested critical nuances in school firearm violence regarding the situations they encompass, the characteristics of the perpetrator and victims, and the location of the incident on school grounds. For instance, this violence encompassed various scenarios, including interpersonal assaults, self-harm incidents where the shooter was the only victim, accidental gun discharges, and legally justified shootings. At the same time, mass casualty shootings (defined as four or more fatalities) were exceptionally infrequent, representing around 5 percent of all interpersonal assaults at schools. The other 95 percent of these shootings involved one or two victims, most of which were nonfatal incidents.

Even among the fatal and nonfatal interpersonal assaults involving known perpetrators, we found that gun violence at American schools displayed considerable variability. Although adults were responsible for almost 29 percent of such incidents, a significant majority (71 percent) involved young individuals aged between 6 and 19. Interestingly, many school shootings were carried out by individuals not enrolled in the schools, often occurring outside school buildings and outside school hours. These incidents were largely fueled by nonacademic concerns, such as personal disagreements or gang-related activities. Therefore, contrary to popular belief, multiple-victim attacks by troubled students account for just a minority of total cases. As such, it is beneficial for policymakers to differentiate between incidents of school shootings that take place within the school during school hours and those that occur outside the school buildings when the school is not in operation. Depending on the specific nature of each incident, tailored intervention strategies are essential. Just as responses to premeditated mass shootings differ from spontaneous assaults, there will be important qualitative differences here between cases that affect how officials prepare, prevent, and respond to school shootings.

In this brief, we present new insights from TASSS, diving deeper into the database’s potential to examine the locations, timing, and student involvement of youth-perpetrated gun violence. In the end, our goal is to equip stakeholders with the essential data they need to formulate effective policies that mitigate school violence.

Read the policy brief.