Police did not identify the suspect or say what might have motivated the shooting rampage at YouTube. However, MSNBC said investigators believe a woman in her 30s approached an outdoor patio and dining courtyard on the campus around lunchtime and began to fire before entering the building.
Senior law enforcement officials believe the shooting stemmed from a domestic dispute, MSNBC and other media reported. A US government security official told Reuters there was no known connection to terrorism.
In a statement issued via Twitter, San Bruno Police Department said they “arrived on scene at 12:48pm, two minutes after the first call, and immediately began searching for a possible suspect.
The four patients taken to San Francisco General Hospital were all awake, Dr Andre Campbell a trauma surgeon at the hospital said at a news conference.
The three people were victims of gunshot wounds, Campbell said, but none of them had undergone surgery. A fourth person was taken to the hospital with an ankle injury from fleeing the scene.
One of the victims, a 36-year-old man, was listed in critical condition at San Francisco General Hospital. A 32-year-old woman was listed in serious condition and a 27-year-old woman in fair condition.