The leaders of the House Homeland Security Committee are demanding the owner of the online message board 8chan come before lawmakers following a wave of shootings in which the suspected gunmen posted extremist and racist screeds on the site.

In a letter Tuesday, Committee Chairman Bennie Thompson, D-Miss., and ranking member Mike Rogers, R-Ala., requested 8chan owner Jim Watkins’ presence before the panel to discuss how he is addressing the spread of extremist content on the platform.