US Capitol Police said Wednesday that several guns were recovered and three people were taken into custody when officers examined a suspicious vehicle near the Capitol.
An 81-year-old man was arrested on weapons charges, and his adult grandson was turned over to DC Disability Services. A third woman was detained with them and released.
According to Capitol Police, officers noticed a white van was parked illegally and a police dog alerted officers to the search. One of the men told officers that he had guns, which are still banned in the Capitol grounds.
Capitol Police said officers found two grenades and a shotgun in the vehicle.
When officials investigated, many roads in the area were closed. Police said on Wednesday evening that they would start reopening the roads.
The nearby Supreme Court was not open on Tuesday, but tight security arrangements have been made in the area. An eight-foot fence erected this spring after several judges received threats was recently removed from around the courtroom.
A 1967 law prohibits bringing guns into Capitol grounds, although members of Congress are given an exception to carry them to and from their offices. Firearms are prohibited from the House and Senate floors and other select rooms, such as the cloak room or adjoining lobby.
Gillian Morley, Michael Kaplan, Scott MacFarlane and Jan Crawford contributed to this report.