Update (4:11 pm):
The emerging details about today's incident that began near the White House and ended near the federal Capitol Building tell a bizarre tale about a woman in a car, reportedly with a child inside, who first crashed into a gate, then led Secret Service agents and Capitol Police on a high-speed chase, and ended with a car crash. It seems to be an isolated incident and no motive of any kind has yet been indicated. The woman has died, according to reports, but it is not clear if her death resulted from gun shots or from injuries suffered in the crash. The child is reported to be in custody and not seriously injured, at least physically.
The Associated Press reports:
A woman driving a black Lexus tried to ram through a White House barricade Thursday, then led police on a chase that ended in gunfire outside the Capitol, witnesses and officials said.
Tourists watched the shooting unfold on Constitution Avenue outside the Capitol as lawmakers inside debated how to end a government shutdown. Police quickly locked down the entire complex for about an hour, and both houses of Congress went into recess.
The pursuit began when a car tried to ram a security barricade blocking the stretch of Pennsylvania Avenue in front of the White House, according to a law enforcement official who was not authorized to discuss the case by name and insisted on anonymity.
Witnesses said at least 20 police cars chased the Lexus toward Capitol Hill, where the car crashed outside the Capitol.
Tourist Edmund Ofori-Attah said he walked toward the scene, curious about what was going on.
"Then I heard the gunfire" and hit the ground, he said.
Senate Sergeant at Arms Terrance Gainer said a woman was driving the car and had a child with her. Ofori-Attah said the child appeared to be about 2 to 3 years old.
Gainer said the child was taken to a hospital.
Capitol Police Chief Kim Dine said the driver was in custody. He did not disclose her condition.
Update (2:59 pm):
News agencies are now reporting that today's incident which resulted in shots being fired on Capitol Hill first originated outside the White House. Those details remain unclear, but Capitol Police have announced a press conference that will begin shortly. The indication is that the "incident" is now over and is not an ongoing crisis.
Original posting (2:31 pm EST):
Gunfire has been reported from Capitol Hill in Washington, DC.
The reports of shots being fired near the Capitol Building and federal offices buildings prompted a lockdown of the area and a large police presence was accumulating near the Rayburn Building, which houses offices for the House of Representives.
Sen. Sherrod Brown (D-OH) and Sen. Bernie Sanders (I-VT) described to NBC News how they heard four shots near 2nd Street and Constitution Avenue.
MSNBC's Luke Russert reported via phone that he heard three to four shots near his office and subsequently saw a helicopter landing on the National Mall.
This twitpic shows it:
— Operator (@911BUFF) October 3, 2013
Early media reports indicated that officers from the Capitol Police may have been "injured" and video footage from the scene showed what looked like a police officer on a medical stretcher being loaded into the helicopter.
The Washington Post reports:
Shots were fired outside the Capitol Thursday afternoon and Capitol Police were telling people to shelter in place. Police say the Capitol was locked down.
Officers with semi-automatic weapons were seen running for the exits on the House side of the Capitol.
As of 2:26, the Senate floor was still open and the Senate was on the floor, but police were in the hallways, reporters on the scene said.