A man accused of involvement in the Jan. 6, 2021, riot at the Capitol was arrested Thursday afternoon near the Washington home of former President Barack Obama, as police found weapons, ammunition and materials that could make explosives inside the suspect’s van, according to a law enforcement official familiar with the case.

Taylor Taranto, 37, of no fixed address, livestreamed his activities before his arrest, including as he drove into the neighborhood and talked briefly with a member of the Secret Service stationed there. On the livestream, he talked about seeking an interview with John Podesta, a Democratic official who has been the focus of far-right conspiracy theories, and also spoke of the neighborhood as containing underground tunnels. He entered a wooded area attempting to take photos of a house.

“I’m outside Barack Obama’s house,” he said at one point on the livestream.

The District of Columbia police, known as the Metropolitan Police Department, said in a statement that Mr. Taranto was charged as a fugitive from justice. The arrest warrant was from the U.S. Capitol Police, but the police did not detail the underlying charges.

Jason Bell, the Capitol Police’s acting assistant chief for protective and intelligence operations, said in a statement that his agency’s officers assisted in the investigation “due to a concern for public safety and the potential for violence against members of Congress.”

Mr. Taranto’s arrest was reported earlier by NBC News.

The officers who arrested Mr. Taranto called in a unit from the city that deals with explosives to perform a sweep of the suspect’s van. The official familiar with the matter said that weapons, materials that could make explosives and several hundred rounds of ammunition were recovered.

Mr. Taranto has been sued by the widow of Officer Jeffrey Smith, a Metropolitan Police Department officer who died by suicide after the violence at the Capitol. The suit alleges that during the attack, Mr. Taranto had handed a cane or crowbar to another man, who used it to assault Officer Smith.

Mr. Taranto has denied doing so.

The official said the investigation into Mr. Taranto was continuing, including into what his purpose was in the neighborhood, a wealthy enclave where the Obamas have owned a Tudor-style mansion since 2017.

It was unclear if the Obamas were home at the time. Mr. Taranto was not inside what the Secret Service defines as the “protective zone” around the house when he was arrested.

“There is no active threat to the community,” the Metropolitan Police Department said in its statement.

Eileen Sullivan contributed reporting.