Female shooter with self-inflicted wounds at YouTube HQ is dead; at least 3 others wounded

SAN BRUNO, Calif. — At least three people have been confirmed injured and one woman is dead from a self-inflicted gunshot wound after an active shooter situation at YouTube headquarters Tuesday afternoon in San Bruno, California.

Investigators believed the unidentified woman was the gunman.

The San Bruno Police Department arrived at the campus in the 900 block of Cherry Avenue near Bay Hill Drive around 12:48 p.m. after receiving multiple 911 calls about shots fired.

"It was very chaotic as you can imagine," Police Chief Ed Barberini said.

The shooter is believed to have known at least one of the victims, two law enforcement officials told CNN.

A spokesman for Zuckerberg San Francisco General Hospital, a level 1 trauma center, said the facility received three patients. One 36-year-old man was in critical condition, one 32-year-old woman was in serious condition and one 27-year-old woman was in fair condition.

One witness inside a cafe near the shooting said the gunfire didn't immediately register with him.

"It was a surprise, because you don't really expect something like that," the man told CNN affiliate KPIX. "I heard some pops, I obviously thought it was balloons, but then I thought that doesn't make sense, not today. Then I heard more shots and that's when everyone started scrambling for the door."

Another YouTube employee said during the shooting people were trying to get out of the building "as fast as they could."

She said she was on a conference call and a colleague, who heard shots, told her at least one person was shot on the patio where people eat.

"We were all suddenly aware of a lot of noises, of sounds, people running outside of the room where she was. And people screaming," said the employee, who was in a building down the street.

" 'I have to get out of here,' " the woman said her colleague said.

A witness told CNN affiliate KRON he heard two or three shots and later about 10 shots. He was at a Carl's Jr. fast-food restaurant across the street from an end of the YouTube building where there are tables with umbrellas on a patio.

A woman ran over to the Carl's Jr. with a leg wound, he said. People at the fast-food restaurant tried to use napkins to stop the bleeding.

Live arial footage from the scene shows dozens of employees evacuating the campus with the aid of local law enforcement.  Some workers tweeted with claims of hearing gunshots fired before employees started scattering around the building and towards the exits.

"We conducted a quick, immediate search of the business when officers arrived,"Barberini said.

So far, no injuries have been reported.

It hasn't been confirmed how many people were inside the building at the time, but nearly 1,100 employees work at the campus. The world’s biggest online video website is located on a suburban campus just south of San Francisco.

Google responded via Twitter with the following message: "[We] are coordinating with authorities and will provide official information here from Google and YouTube as it becomes available."