A gunman killed three people at a UPS facility in San Francisco before killing himself on Wednesday, Assistant Police Chief Toney Chaplin said. According to CNN, two other people were also shot and survived.

Police responded to a report of an active shooter around 8:55 a.m. local time at the UPS San Francisco Customer Centre -- package sorting and delivery facility that employs about 850 people.

Officers arrived to learn the suspect was still inside the building, Chaplin said. A police "contact team" soon found him armed with an assault pistol, the assistant chief said.

"The suspect put the gun to his head and immediately discharged the weapon," he said. Though the suspect was wearing a UPS uniform, investigators have yet to confirm he was actually an employee, Chaplin said.