A picture of the tragedy, and the suspect behind it, is now emerging. Here are the facts that have come to light so far.
Around lunchtime on Tuesday, April 3rd, employees at YouTube's headquarters in San Bruno, California, began reporting gunshots fired in the building. Several employees called 911, and others tweeted about the shooting, including Vadim Lavrusik, whose message was widely cited in early reports.
Three people are being treated for gunshot wounds
A San Bruno police report says that officers arrived on site a few minutes after receiving calls about the shooting. YouTube employees were evacuating the building, and police encountered one person with an apparent gunshot wound, while two others, also wounded, had already left the campus.