Chairman of the House Homeland Security Committee, Rep. Bennie G. Thompson (D-MS), penned letters today to tech executives from companies like Facebook and YouTube requesting a briefing on March 27th regarding their response to the New Zealand shooter’s live stream and the subsequent reuploads across multiple platforms.

Thompson’s letter was sent to Facebook CEO Mark Zuckerberg, YouTube CEO Susan Wojcicki, Twitter CEO Jack Dorsey, and Microsoft CEO Satya Nadella, urging them to prioritize the removal of the terrorist content and to brief the committee on their response and plans to prevent something similar from happening in the future.

The letter was sent in response to the mass shooting that left 50 people dead after a white nationalist opened fire in a mosque in Christchurch, New Zealand, last week. The shooter live-streamed the attack on Facebook, and other users posted copies of the video across social media. On Sunday, Facebook said that it had removed nearly 1.5 million videos of the attack and YouTube said it had removed an “unprecedented volume” of videos.

“I was deeply concerned to learn that one of the shooters live-streamed this terror attack on Facebook, and the video was subsequently reuploaded on Twitter, YouTube, and other platforms,” Thompson said. “This video was widely available on your platforms well after the attack, despite calls from New Zealand authorities to take these videos down.”

A spokesperson for Facebook confirmed that the company would brief the committee “soon,” but they did not specify an exact date or who would provide the briefing. A YouTube representative only referred back to an earlier statement on the volume of uploads. Microsoft and Twitter did not immediately respond to requests for comment.

“You must do better,” Thompson wrote. “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.”