"The employee worked as a cutter," Tucson Police spokeswoman Sgt. Kimberly Bay told CNN. "He was separating metal and cut into a piece that turned out to be military ordnance. No one else was injured."

Police evacuated the remaining employees, and a bomb squad took over the investigation. Davis-Monthan Air Force Base provided assistance.

"They don't know how that ordnance ended up at the facility or where it came from," Bay said. "There is no indication there are other explosives there."

OSHA is launching an independent investigation. The man has not been identified yet.