According to authorities, a shooter appeared to livestream video of the attack on Facebook, documenting the attack on Facebook from the drive to the Al Noor Mosque from a first-person perspective, and it showed the shooter walking into the mosque from the auto and opening fire.
"New Zealand Police alerted us to a video on Facebook shortly after the livestream commenced and we quickly removed both the shooter's Facebook and Instagram accounts and the video". "We are working with social media platforms, who are actively removing this content as soon as they are made aware of an instance of it being posted".
Mia Garlick of Facebook's New Zealand policy team said the social network was working to prevent repostings of the violent video.
About 70 others also received the screed moments before Friday attacks, including National Leader Simon Bridges and domestic and global media, the New Zealand Herald reported. In response, YouTube said it's "working vigilantly to remove any violent footage".
"The responsibility for content of the stream lies completely and exclusively on the person who initiated the stream".
New Zealand police have also asked social media users to stop sharing footage of the incident. Earlier previous year, YouTube star Logan Paul posted a clip of a dead body hanging from a tree in Japan, prompting the Google-owned video portal to remove his channels from a preferred advertising program.
All platforms encourage reporting such videos.
Facebook yesterday acknowledged the challenge and said it was responding to new user reports.
Twitter has also been battling to remove shared videos.
In footage that at times resembled scenes from a first-person shooter video game, the mosque shooter was seen spraying terrified worshippers with bullets, sometimes re-firing at people he had already cut down.
People who wanted to spread the material had raced to action, rapidly repackaging and distributing the video across many apps and websites within minutes.
Yesterday, just before the alleged gunman opened fire in Christchurch, he urged viewers to subscribe to the popular YouTube channel PewDiePie, which itself has been criticised for posting offensive footage in the past.
"This is a case where you're giving a platform for hate", he said.
In 2017, a father in Thailand broadcast himself killing his daughter on Facebook Live.
Hours after the shooting, Reddit took down two subreddits known for sharing video and pictures of people being killed or injured -R/WatchPeopleDie and R/Gore - apparently because users were sharing the mosque attack video.
U.S. President Donald Trump posted a tweet condemning the "horrible massacre", as did former leader Barack Obama.
"Extremists will always look for ways to utilise communications tools to spread hateful ideologies and violence", she said.