Mia Garlick of Facebook's New Zealand office said in a statement to American internet media BuzzFeed journalist Ryan Mac that the company is working to block the shooting video from spreading in the Facebook community.
Brenton Tarrant livestreamed the murder of 49 people in two mosques in Christchurch, New Zealand, on Friday morning after posting links to a manifesto and images of the weapons on Twitter.
Last year, a live-streamed video game tournament was cut short after a shooter entered the Esports arena and opened fire.
Facebook is "removing any praise or support for the crime and the shooter or shooters as soon as we're aware", she said.
According to reports, following the massacre, several world leaders have criticized Facebook over its role in circulating this kind of content with the Prime Minister of New Zealand, Jacinda Ardern indicating that she wants to carry out discussions with the company over its live streaming feature.
So far only Facebook has released any meaningful figures, saying it stopped 1.2 million video play attempts out of 1.5 million at the point of upload in the first 24 hours, although critics suggest the total number of plays was much higher.
While platforms including Twitter and YouTube said they moved fast to remove the content, users reported that it was still widely available hours after being first uploaded to the alleged shooter's Facebook account.
Downing Street has also demanded United Kingdom news and media companies remove from their websites terrifying footage.
This article has been adapted from its original source.
"One of the most complex global governance challenges confronting the worldwide community is the norms of how social media is to be regulated - with the added complexity that the objects of such norms are no longer sovereign states, but private businesses with platforms larger than most countries by population". In 2015, a local news crew in Virginia was shot dead by a gunman, who subsequently posted his own video of the shooting to Twitter.
Facebook initially missed the livestream of the attack on Friday.
NZ police have asked the public not to share the "extremely distressing" video on any social media platform.
As Peter Kafka quoted Facebook boss Mark Zuckerberg in Recode from a post relating to the spread of misinformation by Russians on the platform in 2017; these platforms put no roadblocks to the spouting of hate speech and now a terrorist attack before it has actually happened.
YouTube said on Twitter: "Our hearts are broken over today's bad tragedy in New Zealand".
A Downing Street spokeswoman said: "They have taken action to take it down and we are clear that all companies need to act more quickly to remove terrorist content. Social media firms have made the decision not to invest in adopting it".
The IAB figures showed that only $41.96 million goes to the social media category; however, this figure doesn't account for all the money spent through bookings directly with Facebook.