A school shooting is an attack at an educational institution, such as a primary school, secondary school, high school or university, involving the use of firearms. Many school shootings are also categorized as mass shootings due to multiple casualties. The phenomenon is most widespread in the United States, which has the highest number of school-related shootings, although school shootings have taken place elsewhere in the world. Especially in the United States, school shootings have sparked a political debate over gun violence, zero tolerance policies, gun rights and gun control.