Share of mass public shooters U.S. 1999-2024, by location/relation to shooting site

From 1966 to January 2024, all mass public shooters who carried out shootings at a post office or at a warehouse or factory in the United States were considered 'location insiders', as 100 percent were found to have an existing relationship to the shooting site. In contrast, mass shootings which took place in retail locations had a greater chance of being conducted by someone unaffiliated with the location; within the provided time period, 83 percent of mass public shooters behind retail shootings were seen as outsiders to their chosen shooting site. Similarly, the majority of mass public shooters who chose a restaurant, bar, or nightclub as the site of shooting had no existing relationship to these locations, at 79 percent. The source defines a mass public shooting as: “a multiple homicide incident in which four or more victims are murdered with firearms—not including the offender(s)—within one event, and at least some of the murders occurred in a public location or locations in close geographical proximity (e.g., a workplace, school, restaurant, or other public settings), and the murders are not attributable to any other underlying criminal activity or commonplace circumstance (armed robbery, criminal competition, insurance fraud, argument, or romantic triangle). Mass shootings attributable to gangs, as well as most domestic homicides, are therefore excluded from this definition.

自1966年至2024年1月，所有在美国邮政局、仓库或工厂等地实施枪击事件的公众大规模枪击者均被视为‘场所内部人士’，因为100%的枪击者被发现与枪击现场存在既有的联系。相比之下，发生在零售场所的大规模枪击事件更有可能由与场所无关联的人员实施；在所提供的时间段内，83%的零售场所枪击事件背后的公众大规模枪击者被视为其选择枪击场所的外部人士。同样，大多数选择餐厅、酒吧或夜总会作为枪击场所的公众大规模枪击者与这些地点也没有既有的联系，占比达到79%。该来源将大规模公众枪击事件定义为：‘在一次事件中，使用枪支杀害四名或以上受害者——不包括犯罪者——且至少部分谋杀发生在公共场所或地理位置紧密相邻的地点（例如，工作场所、学校、餐厅或其他公共场所），且谋杀行为不可归因于任何其他潜在的犯罪活动或日常情境（如武装抢劫、犯罪竞争、保险欺诈、争吵或恋爱关系）。因此，由帮派引起的枪击事件以及大多数家庭暴力谋杀事件均不包含在此定义之内。’