Man Who Broke Into Pelosi’s Office and Others Are Charged in Capitol Riot

“The goal here is to identify people and get them,” Mr. Kohl said.

The Washington police have also arrested dozens, mostly on charges of unlawful entry and curfew violations.

One of the most serious federal cases involved Lonnie L. Coffman of Falkville, Ala. In the bed of his truck, officers found what they described as an M4 assault rifle and magazines loaded with ammunition. They also found rags, lighters and 11 glass Mason jars filled with a liquid later identified as gasoline.

Bomb technicians determined that they were meant to be turned into Molotov cocktails — small, hand-thrown fire bombs. Mr. Coffman was arrested when he tried to return to his truck around 6:30 p.m. Wednesday. The police found two handguns in his pants pockets, a 9-millimeter handgun in his right front pocket and a .22-caliber pistol in his left front pocket.

When questioned by the police, Mr. Coffman said his Mason jars contained “melted Styrofoam and gasoline,” which would have behaved similarly to napalm when ignited.

Also among those arrested was Derrick Evans, a newly elected lawmaker from West Virginia, Mr. Kohl said. Mr. Evans posted video to his Facebook page of him filming as he stood among the crowd outside a Capitol door, shouting, “There we go! Open the door!” and chanting, “Our house! Our house!” before rushing inside. “We’re going in!” he added.

Though he deleted the video, the F.B.I. found a copy on Reddit.

Another man taken into custody, Richard Barnett, 60, from Gravette, Ark., had posted a picture on social media of himself sitting at Ms. Pelosi’s desk with his feet up and had said he expected to be arrested. “I’ll probably be telling them this is what happened all the way to the D.C. jail,” Mr. Barnett told a reporter later on Wednesday.

The images of Mr. Barnett were “shocking” and “repulsive,” said Jeffrey A. Rosen, the acting attorney general.