Update 7.50pm: A shooting at a UPS warehouse in San Francisco has left four people dead, including the shooter.
San Francisco police Sergeant Toney Chaplin said at a news conference that two others were wounded.
He said the shooter shot himself, and police have not determined a motive.
Earlier: San Francisco police have reported a shooting at a UPS warehouse.
Reports state that the incident occurred near 17th and Vermont streets, near the Bayshore Freeway.
Residents have been warned to stay away from the area because of heavy law enforcement activity.
There is no information on injuries yet.
More as we get it.