Preliminary autopsy results indicate that a U.S. airman was drunk when he opened fire in a Grand Forks Wal-Mart store, killing one worker and injuring a second employee before killing himself.

Police Lt. Derik Zimmel says 21-year-old Marcell Willis had a blood-alcohol level of 0.19, more than double North Dakota's legal limit for driving of 0.08.

Willis was a senior airman stationed at Grand Forks Air Force Base. Police say he walked into the store about 1 a.m. on May 26 and shot and killed 70-year-old cashier Gregory Weiland. Willis then shot and wounded 47-year-old overnight grocery general manager Lisa Braun, who was released from a hospital over the weekend.

Willis then killed himself. The autopsy concluded that he died of a gunshot wound to the head.