"School violence is youth violence that occurs on school property, on the way to or from school or school-sponsored events, or during a school-sponsored event. A young person can be a victim, a perpetrator, or a witness of school violence. Youth violence includes various behaviors. Some violent acts-such as bullying, slapping, or hitting-can cause more emotional harm than physical harm. Other forms of violence, such as gang violence and assault (with or without weapons), can lead to serious injury or even death."
Centers for Disease Control and Prevention: http://www.cdc.gov/