Police said they were responding to an active shooter at a YouTube building in San Bruno, California, on April 3.Videos shared on social media showing people fleeing the area. People both inside the YouTube building and neighboring buildings were reportedly placed on lockdown.This footage shows a number of emergency vehicles and personnel surrounding the building and civilians moving clear of the area. The uploader also streamed live on Facebook for more than an hour-and-a-half. That video includes footage of police and other emergency responders rushing into the building and people being evacuated with their hands above their heads. Credit: Semir Velikarnadsky via Storyful