Facebook removed 1.5 million videos of the Christchurch mosques attacks globally in the first 24 hours after it was posted, it says.
The accused gunman live-streamed the attacks on social media.
Facebook said it was also removing all edited versions of the video that did not show graphic content.
Prime Minister Jacinda Ardern said Facebook's chief operating officer Sheryl Sandberg had sent condolences over the shootings.
She was asked at a press conference whether Facebook should stop live-streaming, and said it was an issue she would look to discuss directly with Facebook.
In the first 24 hours we removed 1.5 million videos of the attack globally, of which over 1.2 million were blocked at upload...— Facebook Newsroom (@fbnewsroom) March 17, 2019