Fifteen mass shootings at U.S. schools since 1999’s massacre at Columbine High School in Colorado have killed a total of 175 victims. That’s according to a database compiled by The Associated Press, USA Today and Northeastern University, in addition to other AP reporting. Mass shooters have killed hundreds of people throughout U.S. history in realms like stores, theaters and workplaces. But it is in schools and colleges where the carnage reverberates perhaps most keenly. The database defines a mass shooting as resulting in the death of four or more people, not including the perpetrator.
