US Capitol security officials who were ousted in the wake of the 6 January attack on Congress have blamed intelligence failures for the breach.
Testifying to a Senate committee, the officials said that the rioters “came prepared for war” with weapons, radios and climbing gear.
Ex-Capitol Police Chief Steven Sund said he had prepared for a protest, not “a military-style coordinated assault”.
Four people died after pro-Trump protesters stormed the US Capitol.
Three of the four officials testifying on Tuesday to the Homeland Security and Governmental Affairs Committee resigned in the immediate wake of the attack, in which one Capitol Police officer was killed.
Acting Washington DC police chief Robert Contee III told lawmakers, who are holding the first public hearing into the attack, that he was “stunned” by how long it took for the Pentagon to deploy National Guard troops to help quell the riots.