Ahead of riot, Capitol Police knew of potential for violence, official says U.S. Capitol Police officers stand watch outside the Senate as lawmakers vote on procedures to proceed with the impeachment of former President Donald Trump for inciting the January 6, 2021, attack on the Capitol by pro-Trump supporters, at the Capitol in Washington, Tuesday, Jan. 26, 2021. (AP Photo/J. Scott Applewhite) (AP) Rachael Levy , The Wall Street Journal Acting police chief says department’s board turned down a request for National Guard support two days before the attack Share Via Read Full Story The U.S. Capitol Police knew before the Jan. 6 rally by supporters of former President Donald Trump that the event could turn violent, but the department didn’t sufficiently prepare, the acting police chief said Tuesday.