A woman opened fire at the company's San Bruno campus on Tuesday, wounding at least three people before she shot and killed herself, police say.
"This is a terrible day in the United States. Once again, we have a mass casualty situation that is confronted here at Zuckerberg SF General Hospital," said Dr. Andre Campbell, a trauma surgeon at Zuckerberg SF General Hospital.
VIDEO: Aerial footage shows active shooting situation at YouTube HQ
Watch the video above to hear what he had to say.
Click here for full coverage on the shooting at YouTube's headquarters.
PHOTOS: Powerful images from shooting at YouTube HQ in San Bruno