An armed employee walked into a Manhattan Home Depot on Sunday and fatally shot his manager before killing himself amid scores of horrified colleagues and shoppers, the authorities said.

Gunfire erupted in the lighting department at the store, on West 23rd Street in Chelsea, about 2:45 p.m., police officials said, sending workers and shoppers streaming out of exits and into the street.

The manager, 38, was shot at least three times; he died at Bellevue Hospital Center.

After shooting the manager, the gunman, 31, shot himself in the head, the police said. Just over two hours after the shooting, his body was still at the scene.

Officials said they would not identify the two men until their families were notified, and that a motive was not immediately clear.