The attack was teased on Twitter, announced on the online message board 8chan and broadcast live on Facebook. The footage was then replayed endlessly on YouTube, Twitter and Reddit, as the platforms scrambled to take down the clips nearly as fast as new copies popped up to replace them. In a statement on Twitter, Facebook said it had “quickly removed both the shooter’s Facebook and Instagram accounts and the video,” and was taking down instances of praise or support for the shooting. YouTube said it was “working vigilantly to remove any violent footage” of the attack. Reddit said in a statement that it was taking down “content containing links to the video stream or manifesto.”
Source: A Mass Murder of, and for, the Internet – The New York Times