Victor Hoffman was 21 years old at the time and had been released from a mental hospital just three weeks before the murders. On the morning of August 15, he entered the Petersons' farm armed with a .22-calibre Browning pump-action repeater rifle. He then proceeded to shoot all but one of the members of the Peterson family, seven of them children, at close range around the four-room house. According to police, 28 shots were fired in total, of which 27 found their target.