UPDATE (5:30 p.m.) - Sources tell NBC News that the female driver involved did not have a gun, and that all shots fired were from law enforcement.
(NECN/NBC News: Steve Handelsman, Washington) - Gunshots were fired outside the U.S. Capitol building in Washington, D.C. Thursday, which prompted a lockdown of the entire building.
The shooting unfolded following a police chase up Constitution Avenue toward the Capitol building.
NBC News reports the suspect, a female, has been shot and killed by police.
Some witnesses say they heard a quick succession of shots, including as many as 12 shots fired in this incident.
U.S. Capitol Police says this does not appear to be terrorism and say it was a solo female suspect, and she had a child in the vehicle.
Police sources tell NBC News the female suspect is dead.
Police say the incident started at the White House, when a female driver rammed her car into a gate and failed to smash her way in.
Pursued by the Secret Service, she reportedly head toward the U.S. Capitol, which would soon be surrounded by police.
Confrontation between the suspect and police came near the west side of the Capitol, resulting in rapid-fire gunshots, reported by an NBC News satellite truck operator working near the scene. There was then a car chase, which ended with a crash and the reported arrest of the suspect.
The Capitol Building itself and the six Senate and House office buildings were ordered lockdown, and tourists ran for cover, as lawmakers and staffers were told to shelter in their offices.
A reportedly injured officer was taken to a helicopter that had landed on the west side of the Capitol, and flown away for treatment at a hospital.
The Capitol Building has since been reopened.