A Descriptive Analysis of School and School Shooter Characteristics and the Severity of School Shootings in the United States, 1999–2018

Purpose: The aim of the study was to determine whether characteristics related to the school, shooter, and guns used are associated with school shooting severity (casualty rates, fatality rates, and likelihood of fatality). Methods: We analyzed associations between individual-, school-, gun-level factors and school shooting severity in the United States from April 1999 through May 2018. Results: Handguns were used in most school shootings (81%); however, substantially, more fatalities occurred when rifles (relative risk [RR]=14.74, 95% confidence interval [CI][5.00, 43.41])or shotguns (RR = 8.84, 95% CI [2.20, 35.54])were used. Fatal shootings were more likely to happen in schools that were majority white, taught younger students, and were rural or suburban. When shooters were aged ≥20 years, shootings were more likely to be fatal (RR = 2.44, 95% CI [1.18, 5.07]), have more casualties (RR = 5.15, 95% CI [2.06, 12.90]), and more deaths (RR = 20.13, 95% CI [4.86, 83.28]). No significant differences were observed based on the presence of resource officers. Conclusions: More severe shootings were associated with shooters who were older and therefore unlikely to be students, whereas the presence of a school resource officer was unassociated with any reduction in school shooting severity. Importantly, the type of gun used was strongly associated with casualties and fatalities. Study findings suggest a need for prevention efforts beyond those commonly used in schools, as well as the need for improved laws.