Female Suspect Dead, 4 Wounded in Shooting at YouTube’s HQ in San Bruno, California

Officers run toward a YouTube office in San Bruno, Calif., Tuesday.

The woman appeared to have killed herself and four patients were being treated for gunshot-related injuries, police said.

A woman opened fire at YouTube’s California headquarters Tuesday afternoon before apparently turning the gun on herself, authorities said. Four people were being treated for gunshot-related injuries, at least one of whom was in critical condition.

Zuckerberg San Francisco General Hospital said it received three patients with gunshot wounds: a 36-year-old man who was in critical condition, a 32-year-old woman who was in serious condition and a 27-year-old woman who was in fair condition. Details of the fourth injury reported by police weren’t immediately available, but authorities said some people may have been injured fleeing the scene.

“This is a terrible day in the United States, when once again we have a multiple-casualty situation that has confronted us,” Andre Campbell, a surgeon at Zuckerberg, told reporters.

San Bruno Police Chief Ed Barberini said the shooter appeared to have killed herself.

“It was very chaotic, as you can imagine,” Barberini said.

Senior law enforcement officials said the woman, who appeared to be in her 30s, approached an outdoor patio and dining area near lunchtime and opened fire. They said the shooting appeared to have stemmed from a domestic dispute and wasn’t related to terrorism.

YouTube employees tweeted that they had evacuated the building in San Bruno, south of San Francisco, or were in hiding.

Barberini said San Bruno police began receiving multiple 911 calls of an “active shooter” at 12:46 p.m. (3:46 p.m. ET) and were on the scene within two minutes. The Federal Bureau of Alcohol, Tobacco, Firearms and Explosives and the FBI said they also responded to the scene.

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SOURCE: NBC News – Alex Johnson and Andrew Blankstein