Story highlights Gunman identified as Jimmy Lam, source says

Three men killed identified by medical examiner's office

San Francisco (CNN) The gunman who killed three men at a UPS facility in San Francisco and then killed himself has been identified as 38-year-old Jimmy Lam, said a source close to the investigation.

The victims were Wayne Chan, 56, and Benson Louie, 50, both of San Francisco; and 46-year-old Michael Lefiti of Hercules, California, the city's medical examiner said.

Two others were shot but survived the Wednesday shooting at the UPS San Francisco Customer Center, police said.

Officers responded to a report of an active shooter about 8:55 a.m. local time (11:55 a.m. ET) at a package sorting and delivery facility, a couple of blocks east of Franklin Square.

When officers went inside the building, they found the suspect armed with an assault pistol, Assistant Police Chief Toney Chaplin told reporters.

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