A woman believed to be the shooter at YouTube headquarters is dead of a “self-inflicted gunshot” and four others have been wounded, police in California have said.
San Bruno Police chief Ed Barberini told reporters the victims have gunshot wounds and were taken to hospitals.
A spokesman for San Francisco General Hospital says it received three patients.
Spokesman Brent Andrew said a 36-year-old man is in critical condition, a 32-year-old woman is in serious condition and a 27-year-old woman is in fair condition.
He said the hospital was expecting more patients but does not know their conditions.
TV helicopter video shows officers searching people grouped outside a building and police vehicles surrounding the area.
A spokeswoman for California’s Stanford Hospital said it had received four to five patients from the shooting at YouTube but had no information about their condition.
San Bruno police said they could not provide more information about the incident.
The world’s biggest online video website is located on a suburban campus.
Calls and emails to YouTube representatives were not immediately returned.
YouTube employee Vadim Lavrusik posted on Twitter that he heard gunshots and saw people running.
He said he was barricaded in a room with his co-workers before being safely evacuated.
Will Hudson said his friend who works for YouTube texted him about the assailant.
“I think there might be a shooter in my building,” read one text.
“The fire alarm went off so we started to evacuate and then people (started) running saying there was a shooter.”
Mr Hudson said his friend has made it safely back to San Francisco and is in contact with his family.
Mr Hudson said he had become accustomed to hearing about such violence but has never been so close to it before.
“It just feels strange. It feels like it could really be anyone. That’s really the strangeness of it,” he said.
The White House said President Donald Trump had been briefed on the shooting.