Updated 22:35
US Police say a woman suspected of carrying out a shooting rampage at YouTube's headquarters in California is dead.
In a press briefing, San Bruno Police Chief Ed Barberini said four people were injured in the attack.
He said one woman, believed to be the shooter, died from a suspected self-inflicted gun-shot wound.
San Francisco General Hospital has confirmed that it received three victims from the incident.
Brent Andrew, a spokesperson for the hospital, said two women and one man had been admitted.
He said one of those is in a critical condition. Of the other two, one is in a serious condition and another is described as fair.
Chief Barberini said officers are currently clearing the building:
“We have four victims who have all been transported for gunshot related injuries," he said.
"And we have one subject who is deceased inside the building with a self-inflicted wound who, at this time, we believe to be the shooter but we are still following up on that."
Police officers near YouTube headquarters in San Bruno, California, 03-04-2018. Image: Jeff Chiu/AP/Press Association Images
US President Donald Trump has thanked the "phenomenal law enforcement officers and first responders that are currently on the scene" saying his "thoughts and prayers are with everybody involved."
Was just briefed on the shooting at YouTube’s HQ in San Bruno, California. Our thoughts and prayers are with everybody involved. Thank you to our phenomenal Law Enforcement Officers and First Responders that are currently on the scene.
— Donald J. Trump (@realDonaldTrump) April 3, 2018
A witness at the scene said a SWAT team and armed police had surrounded the building.
Earlier police urged the public to "stay out of the area."
We are responding to an active shooter. Please stay away from Cherry Ave & Bay Hill Drive.
— San Bruno Police (@SanBrunoPolice) April 3, 2018
Police activity at 901 Cherry Ave, please stay out of the area. pic.twitter.com/H6iAj0g7ra
— San Bruno Police (@SanBrunoPolice) April 3, 2018
YouTube product manager Vadim Lavrusik posted on Twitter: "Active shooter at YouTube HQ. Heard shots and saw people running while at my desk. Now barricaded inside a room with coworkers."
Active shooter at YouTube HQ. Heard shots and saw people running while at my desk. Now barricaded inside a room with coworkers.
— Vadim Lavrusik (@Lavrusik) April 3, 2018
Another Youtube staff member told CNN she was on a video call with a colleague inside the effected building when the incident began:
"We were all suddenly aware of a lot of noises and sounds of people running outside of the room where she was and people screaming," she said.
"The person who was in the room on the video conference in the building suddenly became very alarmed and was listening to the sounds and suddenly became very scared and said, 'I have to get out of here.'"
Images posted on social media showed people being lead with their hands up outside YouTube's office.
BREAKING: Mass evacuation underway at the #YouTube headquarters in California. Active shooter reported #Breakingnews #usa #nra #shooter #activeshooter pic.twitter.com/WQ3diWeNdQ
— Faizz (@fzc77) April 3, 2018
YouTube product manager Todd Sherman said he was in a meeting when he heard people running for the exit.
He said it “seemed serious and not like a drill.”
We headed towards the exit and then saw more people and someone said that there was a person with a gun. Shit.
— Todd Sherman (@tdd) April 3, 2018
I looked down and saw blood drips on the floor and stairs. Peaked around for threats and then we headed downstairs and out the front.
— Todd Sherman (@tdd) April 3, 2018
In a string of tweets YouTube owner Google confirmed it was coordinating with local authorities in relation to the incident.
It said its security team has been working to help police “evacuate the buildings and ensure the safety of employees in the area.”
The company warned its employees to stay away from the area, adding “there is no need to take any action.”
A special helpline has been set up for employees.