Mass shootings since Sandy Hook, in one map
Vox - 08/21/2015
But not everyone agrees with this definition. Northeastern University criminologist James Alan Fox, for example, defines mass shootings as any shooting in which at least four people were murdered. Under those terms, mass shootings don’t appear to be increasing. Researchers from the Harvard School of Public Health call that definition too broad, since it catches domestic, gang, and drug-related shootings that aren’t usually considered mass shootings in layman’s terms.