Police agents block access near the Library of Congress in Washington, this Thursday, August 19, 2021. Photo: EFE.

Police evicted several buildings in the area surrounding the building after officers saw the man, whose identity has not been released, holding what appears to be a detonator, the US Capitol Police Chief said. J. Thomas Manger.

Police negotiators communicated with the man, who writes notes and shows them to authorities from inside the vehicle, according to three people who were not authorized to discuss the matter publicly and who spoke on condition of anonymity. reported AP.

"My negotiators are working hard to try to reach a peaceful solution to this incident," Manger said.

"We are trying to get as much information as possible to find a way to resolve this peacefully."

The episode began around 9:15 a.m., when the unmarked van pulled onto the sidewalk outside the library, Manger said.

The driver told police he had a bomb, and was holding what officers believe to be a detonator.

Police deployed snipers in the area near the Capitol and Supreme Court and evacuated several buildings that make up the Capitol complex.

Congress is in recess this week, but personnel were seen walking calmly out of the area heading to agents.

The nation's capital has experienced a tense period since the assault on the Capitol on January 6 by supporters of then-President Donald Trump.

A fence had surrounded the Capitol area for months, but was recently removed.

The day before the incident in January, someone left a homemade bomb at the headquarters of the Democratic National Committee and the Republican National Committee in Washington.

There have been no arrests for the planting of the bombs.

Police cars and barricades surrounded the area on Thursday, and several fire trucks and ambulances were installed nearby.

The Metropolitan Police of the District of Columbia, the FBI and the Department of Alcohol, Tobacco, Firearms and Explosives (ATF) also responded.

The White House said it is monitoring the situation and law enforcement is keeping it informed.

(With information from AP)