A woman opened fire on Tuesday at YouTube's headquarters in San Bruno, California, wounding three people before shooting herself, reports said.
One of those injured was the shooter's boyfriend. Initial investigations show that the shooting stemmed from a domestic dispute, and her boyfriend was the intended target.
Local police believe the shooter acted alone.
During the shooting, employees were evacuated, and took shelter in local cafes and restaurants.
YouTube employee Vadim Lavrusik tweeted, "Active shooter at YouTube HQ. Heard shots and saw people running while at my desk. Now barricaded inside a room with coworkers."
Google, YouTube's parent company, tweeted, "We are coordinating with authorities and will provide official information here from Google and YouTube as it becomes available."