↑ Greenberg, Jacobson & Valverde, Jon, Louis & Mariam (ngày 14 tháng 2 năm 2018). “What we know about mass shootings”. Politifact. Tampa Bay Times. Truy cập ngày 20 tháng 2 năm 2018. As noted above, there is no widely accepted definition of mass shootings. People use either broad or restrictive definitions of mass shootings to reinforce their stance on gun control. After the 2012 Sandy Hook school shooting, Congress defined "mass killings" as three or more homicides in a single incident. The definition was intended to clarify when the U.S. Attorney General could assist state and local authorities in investigations of violent acts and shootings in places of public use.
↑ Ingraham, Christopher (ngày 3 tháng 12 năm 2015). “What makes a 'mass shooting' in America”. Washington Post. Truy cập ngày 5 tháng 11 năm 2017. But starting in 2013, federal statutes defined "mass killing" as three or more people killed, regardless of weapons.
↑ Follman, Mark. “What Exactly Is A Mass Shooting”. Mother Jones. Truy cập ngày 9 tháng 8 năm 2015. In January 2013, a mandate for federal investigation of mass shootings authorized by President Barack Obama lowered that baseline to three or more victims killed.
