The Federal Bureau of Investigation defines a mass shooting as a fatal shooting involving three or more victims.
Mass shootings that occur in public (rather than in a residence) have become increasingly common in the United States. The rise in public mass shootings began in the 1980s and coincides with the rapid increase in the sale of semiautomatic weapons with detachable high-capacity ammunition magazines. As the gun industry sells and markets firearms designed for increased lethality, mass shooters purchase these same weapons to use in their attacks.
VPC research has also found that mass shootings are not infrequently committed by individuals with permits to carry concealed handguns. VPC’s Concealed Carry Killers database has identified at least 35 mass shootings since 2007 involving persons with concealed carry permits.