"Shooting: Sandy Hook Elementary school in Newtown, Connecticut Date: Dec. 14, 2012 Perpetrator: Adam Lanza Guns: First, Lanza shot and killed his mother with a .22-caliber Savage MK II-F bolt action rifle. At the school, Lanza used an AR-15 semiautomatic, like Holmes. Lanza killed 26 people in total and injured two before killing himself. How he got them: Both guns belonged to Lanza’s mother."