A U.S. airman walked into a Wal-Mart Supercenter in North Dakota early Tuesday and opened fire with a handgun, killing one worker and injuring a second before turning the gun on himself, police said.

Grand Forks Police said the shooting that occurred a few minutes after 1 a.m. may have been random, with no link yet found between Marcell Willis, 21, and either the store or the employees.

“We’ve not been able to find any linkage to him and any of the victims. That’s not to say that can’t change,” police Lt. Derik Zimmel said during an afternoon news conference. “There’s no apparent motive that jumps out at this time.”

Authorities did not immediately identify the two workers who were shot or a third worker they say Willis shot at but missed. The injured person was hospitalized with a gunshot wound that was not believed to be life-threatening, Zimmel said. A hospital spokeswoman said the person was listed in “satisfactory condition” Tuesday afternoon.

Willis was given medical treatment at the scene and taken to the hospital, where he was pronounced dead, Zimmel said.

Willis was the only person with a gun and no police officers fired a weapon, according to Zimmel. A handgun was recovered near Willis’ body, Zimmel said.

The Wal-Mart is one of two in the northeastern North Dakota city of about 55,000 people. The store is open 24 hours, though it was closed Tuesday while authorities investigated the shooting. The company said it did not know when the store would reopen.