US Capitol Police said they extracted a man from a suspicious vehicle in front of the US Supreme Court where the nine justices were hearing oral arguments on Tuesday.
“The man is in custody. Everyone is safe,” police said.
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 US 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 US Capitol surrendered to police after a standoff that paralyzed a swath of Washington for more than five hours.