Inside a Deadly Siege: How a String of Failures Led to a Dark Day at the Capitol

With the police in the lead, guns drawn, the group stumbled through the mayhem, Mr. Crow said. Some police officers rushed to barricade other doors to block the mob. Others pinned some rioters to the ground to allow the lawmakers to pass.

Because of efforts to restrict the number of people in the chamber, several lawmakers and aides were sheltering in their offices, scattered across the complex. Some were not contacted by the police, even as they barricaded themselves inside.

Many of the House members remained in one secure location, where they might have been exposed to someone with the coronavirus, the Office of the Attending Physician said on Sunday.

Representative Lisa Blunt Rochester, Democrat of Delaware, pushed a handful of Republicans to wear masks, to no avail. Representatives Hakeem Jeffries, Democrat of New York, and Liz Cheney, Republican of Wyoming, periodically provided updates to the room, as lawmakers called their families and checked on their staff members.

On the Senate side of the Capitol, the rioters came perilously close to lawmakers. As they approached, a quick-thinking Capitol Police officer pushed one of them, then backed away, and the crowd chased him. The officer’s maneuver helped lead the mob away from an entrance to the Senate several feet away, according to a video taken by Igor Bobic, a HuffPost reporter.

In a secure, undisclosed location, Senator Lindsey Graham, Republican of South Carolina, screamed at the Senate sergeant-at-arms, Michael C. Stenger, demanding a plan and ordering him to clear the rioters, according to a person in the room. Mr. Stenger was milling around, the person said, inspiring no confidence that he was in control of the situation. He has since resigned, as has Chief Sund. Throughout the Capitol, urgent voices crackled across police radios giving details about the unfolding siege.

“There was definitely a higher sense of urgency” on police radio traffic as rioters breached the east side of the Capitol, said Ashan M. Benedict, the head of the Washington field office of the Bureau of Alcohol, Tobacco, Firearms and Explosives, who was working with the Capitol Police at the nearby Republican Party headquarters, where a pipe bomb was found.