https://www.cnet.com/news/facebook-youtube-called-to-meet-lawmakers-about-new-zealand-shooting-video/

Even after the social network took down the video and deleted the shooter's account, the clip spread across the internet. Thompson requested a March 27 briefing before the Committee on Homeland Security regarding the companies' response to the sharing of the video and how they plan to prevent similar incidents.

"It is clear from the recent pattern of horrific mass violence and thwarted attempts at mass violence -- here and abroad -- that this is not merely an American issue but a global one," Thompson wrote in the letter addressed to Facebook CEO Mark Zuckerberg, YouTube CEO Susan Wojcicki, Twitter CEO Jack Dorsey and Microsoft CEO Satya Nadella. "Your companies must prioritize responding to these toxic and violent ideologies with resources and attention."