Video of the attack was uploaded many times after the original was removed, and a few hundred thousand videos were viewable on Facebook before being taken down.
But Facebook said it took action within minutes of being contacted by New Zealand police.Further ReadingSocial media sites struggle to contain video of New Zealand shooting
Last week's white nationalist terrorist attack occurred during Friday Prayer at the Al Noor Mosque and the Linwood Islamic Centre in Christchurch, New Zealand, and killed 50 people while injuring 50 more.
Today, New Zealand Prime Minister Jacinda Ardern said in a speech at Parliament that social media sites must be accountable for what is published on their platforms.
Facebook's update yesterday seems designed to demonstrate that the social network made reasonable efforts to prevent the video's spread despite factors outside its control.
Facebook's post didn't say how many videos or copies of videos have been removed since the first 24 hours after the attack.