A gunman who killed 49 people at two New Zealand mosques live-streamed the attacks on Facebook for 17 minutes using an app designed for extreme sports enthusiasts, with copies still being shared on social media hours later.
The live footage of yesterday's attacks, New Zealand's worst-ever mass shooting, was first posted to Facebook and has since been shared on Twitter, Alphabet Inc's YouTube and Facebook-owned Whatsapp and Instagram.
Facebook, Twitter and YouTube all said they had taken steps to remove copies of the videos. Facebook said it had deleted the gunman's accounts "shortly after the livestream commenced" after being alerted by police.
But Reuters found videos of the shooting on all five platforms up to 10 hours after the attacks, which began at 1345 local time in the city of Christchurch. Twitter and Google said they were working to stop the footage being reshared. Facebook did not immediately respond to additional questions.
In a 15-minute window, Reuters found five copies of the footage on YouTube uploaded under the search term "New Zealand" and tagged with categories including "education" and "people & blogs". In another case, the video was shared by a verified Instagram user in Indonesia with more than 1.6 million followers.
The shootings in New Zealand show how the services they offer can be exploited by extremist groups, said Lucinda Creighton, senior advisor to the Counter Extremism Project. She said the attacks were shown live on Facebook for 17 minutes before being stopped.
"Extremists will always look for ways to utilise communications tools to spread hateful ideologies and violence," she said. "Platforms can't prevent that, but much more can be done by platforms to prevent such content from gaining a foothold and spreading."
The gunman filmed and shared the attacks using a mobile phone app called LIVE4. The app is usually used to share videos of extreme sports and live music, but on Friday the footage recreated the carnage of a computer game, showing the attacker's first-person view as he drove to one mosque, entered it and began shooting randomly at people inside.