WASHINGTON -- The United States Capitol was locked down for about a half-hour on Thursday afternoon after law enforcement officers shot and killed a woman who had been chased there in her car from the White House, law enforcement officials said.
The woman, whom the authorities did not identify, had "attempted to pass a barricade" near the White House, said Kim Dine, the chief of the Capitol Police, and struck an officer in the process.
"The guys ran to try to stop her, and she wasn't going to slow down, so they jumped aside," said B. J. Campbell, a tourist from Portland, Ore., who was standing near the White House. "One of the guys grabbed one of those little metal fence sections and shoved it in front of her, across the driveway. She hit the brakes slightly and tried to get around it on the right, but the guy shoved it in front of her again, to try to keep her in."
Mr. Campbell said the woman "hit the gas, ran over the barricade" and hit the officer, who flipped onto the hood of the car and "rolled off into the gutter."
"After she ran him down, she gunned it, and she just went screaming down Pennsylvania Avenue," he said. "They were busy calling on their phones, on the radios. It was like poking a hornet nest. There were guys everywhere. I didn't see anyone with their guns out, but they were sure busy."
Despite attempts by Secret Service officers to pull her over, she sped away from the White House, officials said.
Chief Dine said that the woman's vehicle, a black Infiniti, also struck a police car on Capitol Hill before it crashed into a barricade. Shots were fired, the woman was struck and the authorities took her to a hospital.
A young child was found in the car, the authorities said. It was not clear whether the woman was armed when the authorities fired on her.
"We have no information that this is related to terrorism or is anything other than an isolated incident," Chief Dine said.
A video clip played on cable networks showed police officers with their weapons drawn approaching the stopped vehicle outside the Capitol.
As they got closer, the vehicle backed up and struck a police car, almost hitting one of the officers and then speeding away.
According to a law enforcement official, the woman was driving as fast as 70 miles per hour as she made her way from the White House to Capitol Hill.
The scene inside the Capitol campus was panicked as it became clear that the police were mobilizing for a security threat. Loud buzzers rang out, a jarring sound to hear in a city still on edge from the shootings last month at the Washington Navy Yard. Police officers ran through corridors, their semiautomatic rifles drawn. They quickly sealed off the entrances to hallways and instructed people to remain in place.
Representative Juan Vargas of California said he was walking back toward the Capitol when he heard several loud bangs, which he initially thought might be a car backfiring.
"I heard 'pop, pop,' and honestly I didn't think anything of it," he said.
Then, he said, he saw a police officer charging for him. "I was wondering what's going on, why is this guy coming at me like a maniac? What's the deal here? I didn't understand what had happened."
When the officer noticed that Mr. Vargas was wearing one of the red-and-gold pins that are issued to House members, he told the congressman to remove it because he could be a target.
During the lockdown, the police permitted some members of Congress to walk through the underground tunnel that connects the Capitol to the Senate office buildings.
At one point, Representative Darrell Issa, Republican of California, snapped at the police guarding the entrance to the tunnel, "Let me past, I am going through," as he walked at a fast clip back toward the Capitol.
Edmund Ofori-Attah and his wife, both missionaries from Togo, were about to tour the Dirksen Senate Office Building when the black Infiniti sped by on Constitution Avenue pursued by two police cars. The car hit a barricade as it tried to make a left turn at a police checkpoint, and five to six gunshots were fired, he said.
"We just dropped to the ground," Mr. Ofori-Attah said. "I didn't want to get hit."
When Mr. Ofori-Attah got up a few minutes later, he said he saw the police remove the child from the woman's car.
Brian Johnson, a lobbyist for the American Petroleum Institute, was returning to his car, parked on the Senate side of the Capitol, after showing around his visiting family members when he heard shots.
"My heart just dropped, and we just ran behind my car," he said.
Ashley Southall and Emmarie Huetteman contributed reporting.
This article originally appeared in The New York Times.