A US man who was fired a day earlier from delivery service UPS put on his work uniform, drove to an Alabama package sorting centre and killed two managers, police said.
The gunman, identified by police as Kerry Joe Tesney, was found dead from what police said was a self-inflicted wound.
He entered the building after about 80 drivers had left for the day to deliver packages, UPS said, possibly avoiding even more bloodshed.
"It was a relatively small crew that was remaining," said Steve Gaut, a spokesman for the shipping company.
Pastor Bill Wilks, of North Park Baptist Church, described Tesney, 45, who was married with two children, as having been troubled over his work and financial situation.
"In his own spirit he's been troubled, and he's asked for prayer about that," Mr Wilks said.
"He's just a guy who went through his trials at work. Certainly we have prayed for him."