YouTube said Monday that it has removed “tens of thousands” of videos related to Friday’s Christchurch mosque massacre in the hours after the attacks, and deleted “hundreds of accounts created to promote or glorify the shooter.” “The volume of related videos uploaded to YouTube in the 24 hours after the attack was unprecedented both in scale and speed, at times as fast as one video per second,” a spokesperson for the company said in a statement tweeted by CNN media reporter Oliver Darcy. The Washington Post reports Monday that the company’s crisis management team worked through the night to battle the near-constant uploading of gruesome footage, which was being intentionally repackaged to trick the company’s detection software.

Eventually, the Post reports, YouTube took the unprecedented step of disabling human review and relying on detection software, pulling the option to search for “recently posted” videos. “This was a tragedy that was almost designed for the purpose of going viral,” the company’s chief product officer told the Post, adding that “this incident has shown that, especially in the case of more viral videos like this one, there’s more work to be done.” Facebook announced yesterday that it had removed 1.5 million videos of the attack in just one day.