WATCH: Senate hearing on Capitol attack

Former U.S. Capitol Police Chief Steven Sund testifies before a Senate Homeland Security and Governmental Affairs & Senate Rules and Administration joint hearing on Capitol Hill, Washington, Tuesday, Feb. 23, 2021, to examine the January 6th attack on the Capitol. (Erin Scott/The New York Times via AP, Pool)

Senate Homeland Security and Rules committees are holding a joint hearing on the Jan. 6 Capitol attack starting at 10 a.m.