About 3:30 a.m. Tuesday, an Ohio State custodial employee shot two of his supervisors, killing one of them, and then shot and killed himself, campus police said.

The shooter, 51-year-old Nathaniel Brown, entered an office suite at the OSU Maintenance Building on Tuttle Park Place during his work shift and opened fire, said OSU Chief of Police Paul Denton at a press briefing. Brown was wearing a hoodie, dark clothes and was carrying a backpack. He had two guns with him.

Larry Wallington  Larry Wallington   Nathaniel Brown  Nathaniel Brown   Henry Butler  Henry Butler

There were more than half a dozen employees in the room at the time. According to the 911 call, Brown opened fire in room 107 of the Maintenance Building.

Brown shot and killed Larry Wallington, 48, building services manager. Operations shift leader Henry Butler, 60, was wounded and is in stable condition at the OSU Medical Center. Update: Butler was shot in the left shoulder and is undergoing surgery, said Heather Butler, his daughter. Police said the shooting was “work related.”

Brown started working at OSU in October and was on probation, said Amy Murray, assistant director of OSU media relations. Police say Brown had received a poor performance evaluation recently.

He may have been about to lose his job, a source told The Lantern. He had been scheduled to work Monday night but did not come to work, said the source, who did not want to be identified because OSU told workers they should not talk to the media about the event.

Brown entered the room and specifically asked for Wallington. When he found him, he shot him. Wallington tried to flee and Brown chased him around the room and continue to shoot at him, the source said. Butler was hit by accident.

Police received the 911 call at 3:32 a.m. and responded immediately, Denton said.