A woman who accused YouTube of discrimination has been named as the chief suspect in a gun attack on the company’s headquarters.

Nasim Aghdam, 39, has been identified by police as the attacker who targeted the firm’s complex in San Bruno, California on Wednesday (Australian time).

The official spoke to The Associated Press on the condition of anonymity because they were not authorised to discuss the ongoing investigation.

During the shooting, a woman armed with a pistol wounded three people before fatally shooting herself, police and witnesses said. Officers and federal agents swarmed the headquarters as multiple 911 calls reported gunfire.

MSNBC reported that police believe a woman in her 30s approached an outdoor patio and dining area on the campus around lunchtime and began to fire.

The suspect, Ms Aghdam, had a number of YouTube channels where she blamed her low number of views on “filtering” by the website.

“I’m being discriminated and filtered on YouTube and I’m not the only one,” she said in one video.

There was no known connection to terrorism, a US government security official said earlier in the day.

San Bruno police chief Ed Barberini told reporters three victims had gunshot wounds and were taken to hospital. A fourth person suffered an ankle injury while trying to flee.

“It’s transitioning more from a tactical or active fluid situation to more of a static investigative effort, and we are going to be out here for some time,” he said.

“I can tell you there’s no immediate threat to the community.”

More hostages leaving the building 🙏 #youtubeshooting pic.twitter.com/YBidNGveiq

— Erin (@erinjeanc) April 3, 2018

Spokesman for San Francisco General Hospital Brent Andrew said a 36-year-old man was in critical condition, a 32-year-old woman was in serious condition and a 27-year-old woman was in fair condition.

Google chief Sundar Pichai said in a statement that the situation was contained, and that the company was “very actively monitoring and working with local authorities and hospitals”.

“We’re doing everything we can to support [the victims] and their families at this time,” he said.

Police in the city south of San Francisco had warned people in a tweet to stay away from the address where YouTube, owned by Alphabet Inc’s Google, is based, after responding to reports of the shooter.

San Bruno city manager Connie Jackson said there had been multiple 911 calls reporting a shooting and that police and fire services had responded.

UPDATE: Female shooter in incident at YouTube headquarters in San Bruno, California, is dead, CBS News confirms. pic.twitter.com/ClDjOxMO79

— CBS News (@CBSNews) April 3, 2018

‘I looked down and saw blood drips on the stairs’

Vadim Lavrusik, a product manager at YouTube, tweeted there was an “active shooter at YouTube HQ”.

“Heard shots and saw people running while at my desk. Now barricaded inside a room with co-workers.”

Todd Sherman, another product manager, tweeted that he was sitting in a meeting when he “heard people running because it was rumbling the floor”.

https://twitter.com/tdd/status/981262640830754817

“First thought was earthquake. After exiting the room we still didn’t know what was going on but more people were running. 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. S—!

“I looked down and saw blood drips on the floor and stairs. Peaked [sic] around for threats and then we headed downstairs and out the front. Police cruisers pull up, hopped out with rifles ready and I told them where the situation was as I headed down the street to meet up with a couple team members.”

Local television images showed YouTube employees walking out of the building with their hands raised.

Some 1700 people work at the YouTube HQ. Google said it was “coordinating with authorities” and would provide information as it becomes available.

The White House said Donald Trump had been briefed and that officials were monitoring the situation.

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

-with agencies