House Homeland Security Committee Chairman Bennie Thompson (D-MS) and Mike Rogers (R-AL) sent a letter to Jim Watkins, the owner of the anonymous online forum 8Chan, demanding that he testify before the committee on how to mitigate extremism on his platform.

Reps. Thompson and Rogers demanded that Watkins come before the House Homeland Security Committee to discuss 8Chan’s efforts to “investigate and mitigate the proliferation of extremist content,” which includes “white supremacist content” on 8Chan.

🚨BREAKING🚨: Homeland Security Chairman Thompson & Ranking Member Rogers sent a letter to 8chan owner Jim Watkins demanding he come before Congress and answer questions on the site’s extremist content. cc: @infinitechan pic.twitter.com/8SDSI1rFLj — House Homeland Security Committee (@HomelandDems) August 6, 2019

The two lawmakers wrote the letter to the 8Chan owner in the wake of the August 3 attack in El Paso, Texas, which resulted in the deaths of 22 Americans. The killer reportedly wrote his manifesto describing anti-immigrant and “white supremacist beliefs” on 8Chan before the shooting, which Watkins denied in a video posted to YouTube.

In a separate statement, Chairman Thompson said, “White supremacist terrorism … is on the rise and is now our top domestic terrorism threat.”

The congressmen said that this latest attack serves as the third attack linked to 8Chan, including the mass shooting at the two mosques in Christchurch, New Zealand, which resulted in the deaths of roughly 51 Muslims.

Reps. Thompson and Rogers noted that website infrastructure service provider Cloudflare first described 8Chan as a “cesspool of hate” before suspending its service. Cloudflare CEO Matthew Prince also banned the white nationalist The Daily Stormer, claiming in 2017 that it would not set a “precedent.”

The lawmakers even noted that Fredrick Brennan, the founder of 8Chan, called for the forum to be shut down.

The leading Homeland Security Committee lawmakers said, “Americans deserve to know what, if anything, you, as the owner and operator, are doing to address the proliferation of extremist content on 8Chan.”

They added, “To that end, the Committee on Homeland Security respectfully requests your presence to provide testimony regarding 8Chan’s efforts to investigate and mitigate the proliferation of extremist content, including white supremacist content, on your website.”