U.S. Capitol Police said they extracted a man from a suspicious vehicle parked illegally in front of the U.S. Supreme Court where the nine justices were hearing oral arguments on Tuesday.
After an unsuccessful effort to negotiate with the man, tactical teams moved in and placed him under arrest, Operational Services Bureau Deputy Chief Jason Bell told a news conference.
The man's motive was unclear to police. He refused to speak except to make a statement "to the effect of 'the time for talking is done,'" Bell said.
"At this time no weapons have been found," he said. Capitol Police identified the suspect as Dale Paul Melvin, 55, of Kimball, Michigan.
The department reported the investigation on Twitter and later added that an officer had extracted the driver from a sport utility vehicle and arrested him.
The nine justices began their new term on Monday with their first oral arguments in person in 19 months due to the COVID-19 pandemic.
Law enforcement authorities have been on high alert in the U.S. capital since a deadly Jan. 6 riot by supporters of then-President Donald Trump.
In August, a man who claimed to have a bomb in a pickup truck near the U.S. Capitol surrendered to police after a standoff that paralyzed a swath of Washington for more than five hours.