Law enforcement officials identified the perpetrator of the YouTube shooting as 39-year-old Nasim Aghdam. California news outlets described her as a vegan-themed content creator.

Aghdam's own website featured an array of animal protection videos that were hosted on YouTube, on issues as diverse as bullfighting and shark fin soup.

She had a range of YouTube channels, in English, Farsi and Turkish, as well as one on "hand art."

Watch video 00:44 Shooting at YouTube US headquarters

On her own website, Aghdam accused YouTube of censorship of her videos, targeting her and certain other users so that their videos were harder to find.

She also claimed that the channel had "demonetized" her videos, referring to cutting revenue to content providers whose material was deemed unfriendly to advertising, or those with a subscriber base of less than 1,000.

Local news website Mercury News reported that Aghdam's father had reported her missing after she failed to answer her phone for two days. He told police she might be headed to YouTube because she "hated" the company.

Police walk outside the Califonia YouTube headquarters where Nasim Aghdam opened fire

Found in parking lot hours before attack

The news website reported that police had found Aghdam sleeping in her car in a parking lot the night before the shootings, and had called her family to say that everything was "under control."

Only hours later, there were scenes of terror at YouTube headquarters in San Bruno, just south of downtown San Francisco. Aghdam shot and wounded three people before turning the gun on herself.

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YouTube employee Dianna Arnspiger told The Associated Press news agency that the shooter had worn glasses and a scarf, and that she was using a "big, huge pistol."

Another employee, Zach Vorhies, said he saw the shooter outside yelling: "Come at me, or come get me."

According to the San Francisco General Hospital which was treating the victims, a 36-year-old man was in a critical condition, a 32-year-old woman was in a serious condition and a 27-year-old woman was in a fair condition.

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