Capitol Police investigated a suspicious vehicle on New Jersey Avenue Northwest around 2:10 p.m. Tuesday, according to the Senate sergeant-at-arms.
As many as a dozen vehicles responded to the scene, closing a portion of the street near the Constitution Avenue intersection.
A staging crew working to set up events on the Capitol campus for the American Federation of Government Employees camped out on the stairs of the Russell Senate Office Building after being told to move out of Upper Senate Park.
The workers were assembling a podium and sound equipment for a candlelight vigil scheduled to begin shortly after 5 p.m.
AFGE members intend to march over to the park for a ceremony honoring three fallen corrections officers from the Bureau of Prisons, according to Cory Bythrow, communications director for the union.
As of 4:30 p.m., the vigil was still scheduled to go on, despite yellow police tape blocking access to the area and the officers blocking access to the street.
Bythrow told CQ Roll Call he expected more than 200 members to participate in the vigil, raising awareness for the need for more staffing and equipment at federal agencies.
Capitol Police cleared and reopened Constitution Avenue around 5:30 p.m. Workers proceeded to assemble the stage and speakers for the vigil. Bythrow reported the march would proceed.
Nothing hazardous was found, according to Capitol Police spokesman Shennell Antrobus.
Former Sen. Scott Brown, R-Mass., candidate for U.S. Senate in New Hampshire, holds his hand over his heart during the singing of the national anthem as he waits to take the stage for his town hall campaign rally with Sen. John McCain at the Pinkerton Academy in Derry, N.H., on Monday, Aug. 18, 2014.