Employees at a San Francisco UPS facility fled in terror yesterday morning screaming, “Shooter! Shooter!” as a gunman opened fire, killing three people and wounding two others before turning the weapon on himself as police closed in.

News sources have identified the assailant as 38-year-old Jimmy Lam of San Francisco. A UPS spokesman said Lam – who was wearing a UPS uniform at the time of the attack -- was an employee of the company. He was described in reports as having mental issues and being estranged from his wife.

The police response to the incident was reportedly massive. San Francisco Police Assistant Chief Toney Chaplin said at a press conference yesterday that the armed suspect "put the gun to his head and discharged the weapon," when confronted by the police. No officers fired weapons.

Although the incident is still under investigation, police believe it is not related to terrorism and that the shooter acted alone. Police are busy interviewing witnesses to the carnage, who number in the hundreds.

Two people are hospitalized with gunshot wounds. Five others suffered injuries during the panicked evacuation of the facility.

UPS employs 350 people at that location.