Mass violence is violence directed by one or more individuals (sometimes organized groups or a nation) toward multiple other individuals (random or national, ethnic, religious, or other identifiable groups). The term has been applied, for example, to terrorist events, wartime genocide, disgruntled employees opening fire on other employees, and targeted or rampage school violence. Across history, mass violence attacks have occurred between or toward ethnic groups—nationally (e.g., Whites and African Americans in the United States; conflicts among the Hutu, Tutsi, and Twa in Rwanda) or in specific locations (e.g., inner-city gang wars). Kings, nations, or groups have waged holy wars or genocide on specific religious groups (e.g., the Crusades; Serbian attempts at “ethnic cleansing;” the Nazis' efforts to exterminate the Jews of Europe). Actions have ...