A mass shooting is a violent crime in which one or more attackers kill or injure multiple individuals simultaneously using a firearm. There is no widely accepted definition of "mass shooting" and different organizations tracking such incidents use different definitions. Definitions of mass shootings exclude warfare and sometimes exclude instances of gang violence, armed robberies, familicides and terrorism. The perpetrator of an ongoing mass shooting may be referred to as an active shooter.

The Nepali royal massacre occurred on 1 June 2001 at the Narayanhiti Palace, the then-residence of the Nepali monarchy. Nine members of the royal family, including King Birendra and Queen Aishwarya, were killed in a mass shooting during a gathering of the royal family at the palace. A government-appointed inquiry team named Crown Prince Dipendra as perpetrator of the massacre. Dipendra slipped into a coma after shooting himself in the head.