In the mosque attack that killed 50 people, the assailant streamed a video on Facebook Live.
A US congressional panel said Tuesday it was asking top executives from US tech firms to explain the proliferation online of the "horrific" video of deadly attacks in New Zealand that were streamed on Facebook and then reposted on other platforms.
The House Committee on Homeland Security asked for a briefing by the four tech executives, calling it "critically important" to filter the kind of violent images seen in the video.
The panel asked for a briefing from Facebook chief executive Mark Zuckerberg, YouTube CEO Susan Wojcicki, Twitter CEO Jack Dorsey and Microsoft CEO Satya Nadella.
Committee chair Bennie Thompson said it was troublesome to learn of the video going viral despite the commitment made by the industry's Global Internet Forum to Counter Terrorism.
"Just last week -- nearly two years after you formed GIFTC -- a terrorist exploited your platforms to disseminate across the world a horrific video of mass violence," Thompson said in a letter released to media.
"I must emphasize how critically important it is for you to prioritize the removal of this sort of sensitive, violent content."
In the mosque attack that killed 50 people, the assailant streamed a video on Facebook Live, which was then copied and reposted elsewhere.
Facebook says it removed a staggering 1.5 million videos showing harrowing viral footage of the Christchurch attacks.
The livestream was viewed fewer than 200 times, but social platforms were unable to prevent the video from being widely seen.
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