School shooting is a term use to refer to gun violence primarily in educational institutions, especially the mass murder or spree killing of people connected with an institution. A school shooting can be perpetrated by people who have a mental disorder, expelled students, alumni, faculty members, outsiders, or even regular students who still attend the school. Unlike acts of revenge against specific people, school shootings usually involve multiple intended or actual victims, often randomly targeted. Most of the school shootings that have occurred have ended up with the perpetrators killing themselves and others.