The attack was streamed live on Facebook via what is thought to be a body-mounted camera. A link to the stream was posted on 8Chan, an imageboard site known for a being a hotbed of far-right extremist views.
In a blog published Monday , Facebook said the live video was viewed fewer than 200 times. After the livestream ended, the video was viewed a further 3,800 times before being taken down, Facebook said.
According to Facebook, no one reported the video while it was live, and the first user report came in 12 minutes after the broadcast ended, 29 minutes after it began.
This has been challenged. Jared Holt, a reporter for Right Wing Watch, said he was alerted to the live stream and reported it mid-attack.
"I was sent a link to the 8chan post by someone who was scared shortly after it was posted. I followed the Facebook link shared in the post. It was mid-attack and it was horrifying. I reported it," Holt tweeted . "Either Facebook is lying or their system wasn't functioning properly."
SEE ALSO: Here's what we know about the victims of the mosque mass shootings in New Zealand that killed at least 50 people