Characteristics and Obtainment Methods of Firearms Used in Adolescent School Shootings.

IMPORTANCE: Within gun violence research, the types of firearms involved in US school shootings and the origins of these weapons have not been well explored.

OBJECTIVE: To examine the type, make, and power of firearms involved in school-related gun violence as well as the sources and methods through which adolescents obtained these weapons.

DESIGN, SETTING, AND PARTICIPANTS: This cross-sectional study used descriptive statistics and logistic regression to analyze 253 school shootings executed by 262 adolescents (aged ≤19 years) in the US from January 1, 1990, to December 31, 2016, and to calculate adjusted estimates for missing cases. The data were sourced from The American School Shooting Study (TASSS), which compiles information about these shooting events from open-source materials. Data analysis was performed from June 23, 2023, to July 20, 2023.

EXPOSURES: Firearm type, make, and power.

MAIN OUTCOMES AND MEASURES: The firearm type refers to whether a weapon was a handgun, rifle, or shotgun. The firearm's make differentiates semiautomatic or fully automatic guns from other action mechanisms. The firearm's power refers to the caliber and velocity, distinguished as small, moderate, or higher power. The acquisition source captures from whom the firearm was received. The obtainment method refers to how the shooter obtained the firearm. Estimates were adjusted by total number of documents and TASSS reliability score as well as neighborhood demographic, socioeconomic, and land use variables measured at the census tract level, and were weighted to account for item nonresponse.

RESULTS: A total of 262 adolescents (mean [SD] age, 16.2 [1.9] years; 256 [97.8%] male) were studied. In the adjusted analyses, handguns were the most used weapon in school shootings (85.5%; 95% CI, 80.6%-89.4%). Firearms were predominantly lower (37.0%; 95% CI, 29.9%-44.7%) or moderate (39.7%; 95% CI, 32.0%-47.8%) in power. Adolescents mainly obtained their guns from relatives (41.8%; 95% CI, 31.7%-52.6%), friends or acquaintances (22.0%; 95% CI, 13.2%-34.5%), the illegal market (29.6%; 95% CI, 19.3%-42.5%), strangers or persons who were shot (4.7%; 95% CI, 1.8%-11.6%), or licensed dealers (1.9%; 95% CI, 0.7%-5.2%). Most firearms were procured via theft from relatives (82.1%; 95% CI, 69.4%-90.3%).

CONCLUSIONS AND RELEVANCE: Despite the more frequent use of lower to moderately powered firearms in school shootings, this study's results indicated stability in the use of high-powered weapons in adolescent school shootings throughout the research timeframe. A majority of the firearms were procured from the perpetrator's family or relatives or from friends or acquaintances. These findings may significantly influence discussions around gun control policy, particularly in advocating for secure firearm storage to reduce adolescents' access to weapons.