(BBC) – A woman shot and wounded three people at YouTube’s headquarters in Northern California before killing herself, police say.
A 36-year-old man left in a critical condition is believed to be the suspect’s boyfriend, CBS news reports. Two women, 32 and 27, were also shot.
San Bruno Police Chief Ed Barberini said officers arrived at the scene at 12:48 (19:48 GMT) local time.
Officers found a “chaotic scene” with “numerous people fleeing”, he said.
One employee at a nearby fast food restaurant told Fox station KTVU he had treated a young woman who suffered a gunshot wound to the leg.
He said he had fashioned a makeshift tourniquet from a bungee cord as they waited for first responders.
Images broadcast on local TV stations showed employees leaving with their hands raised. Other footage appeared to show evacuees forming a queue before being individually frisked by police.
Video captured by a nearby helicopter showed a glass door shattered in its centre, with glass fragments strewn across the ground outside.
Mr Barberini said police arriving at the scene found one victim with a gunshot wound at the front of the company headquarters.
Minutes later officers found a woman who appeared to have shot herself, he said.
Two further victims were later found at a nearby business.
YouTube product manager Todd Sherman tweeted that people fled the building in panic as the shooting unfolded.
Another employee, Vadim Lavrusik, tweeted he was barricaded in a room with other staff. He later said he had been evacuated.
President Trump said he had been briefed about the incident.