Facebook said it removed 1.5 million videos from its site within the first 24 hours after a shooter livestreamed his attack on two New Zealand mosques, killing 50 people.

In a series of tweets, Facebook’s Mia Garlick said a total of 1.2 million videos were blocked at the point of upload. Videos that included “praise or support” from the attack were also removed, she said, using a mix of automated technologies — like audio detection — and human content moderators.

Facebook did not say why the 300,000 videos were not caught at upload, representing a 20 percent failure rate.

In the first 24 hours we removed 1.5 million videos of the attack globally, of which over 1.2 million were blocked at upload… — Facebook Newsroom (@fbnewsroom) March 17, 2019

The cherry-picked “vanity” statistics only account for the total number of uploaded videos that Facebook knows about. TechCrunch found several videos posted to Facebook more than 12 hours after the attack. Some are calling on Facebook to release the engagement figures — such as how many views, shares and reactions — were made before the videos were taken down, which critics say is a more accurate measure of how far the videos spread.

The attack on Friday targeted worshippers during morning prayers in Christchurch, New Zealand. Police said they apprehended the shooter about half an hour after reports of the first attack came in.

The 28-year old suspected shooter, charged with murder, livestreamed the video to Facebook using a head-mounted camera, typically used to record sporting events in first-person. Facebook closed the attacker’s account within an hour of the attack, but the video had already been shared across Facebook, Twitter and YouTube. The shooter described himself as a self-professed fascist, according to a “manifesto” he posted shortly before the attacks. The tech companies have faced criticism for not responding to the emerging threat of violence associated with white nationalism, compared to actions taken against content in support of the so-called Islamic State group and the spread of child abuse imagery,

New Zealand prime minister Jacinda Ardern said on Sunday that social media giants like Facebook had to face “further questions” about their response to the event. Facebook second-in-command Sheryl Sandberg reportedly reached out to Ardern following the attacks.

When reached, Facebook did not comment beyond Garlick’s tweeted comments.