Friday’s massacre exemplified the problem of expecting tech companies to self-police content.

The hate-filled terror rampage at two mosques in Christchurch, New Zealand, was meticulously designed to maximize the number of witnesses around the globe, highlighting the difficulty in putting a lid on extremist hate that spreads online.

The horrific mass shooting at two New Zealand mosques that left 49 people dead was live-streamed on Facebook and shared across social media, sparking a scramble by tech giants to remove the sick footage.

The gunman reportedly broadcast 17 minutes of the attack.

“Police alerted us to a video on Facebook shortly after the live stream commenced and we quickly removed both the shooter’s Facebook and Instagram accounts and the video. We're also removing any praise or support for the crime and the shooter or shooters as soon as we’re aware,” Facebook said in a statement.

Facebook said Sunday that it removed or blocked from the social media site 1.5 million videos of a gunman's rampage on two New Zealand mosques that killed 50 people and wounded dozens more.

Mia Garlick, spokeswoman for Facebook New Zealand, said that about 300,000 videos were removed within the first 24 hours of the terrorist attack Friday. More than 1.2 million were blocked at upload, she said.