Washington: A lone gunman entered the US Capitol Visitors Centre on Monday afternoon local time and drew a weapon at the metal detector area, causing the US capital to go into lockdown.
There was confusion in early accounts about what occurred but police said a suspect was taken into custody with wounds after a policeman shot him.
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Shooting incident at the Capitol complex
RAW: A man was shot and is being held by police after attempting to bring a gun into the Capitol building in Washington DC.
Larry Dawson of Tennessee had previously disrupted a session of Congress, according to local and federal law enforcement officials.
He was stopped by Capitol Police after he set off a metal detector trying to enter the Capitol Visitor Centre on Monday (US time), a federal official said. After an argument, Dawson drew a weapon and pointed it at officers, said the official, who was not authorised to speak publicly on the matter.
At least one officer opened fire, shooting the suspect, said Capitol Police Chief Matthew Verderosa. A weapon was recovered at the scene, he added.
Dawson was taken to a hospital for treatment. A female bystander, age 35 to 45, was hospitalised with what Verderosa called "minor" injuries from the incident.
Dawson's motives remain unclear. Mr Verderosa did not identify Dawson by name during a press briefing outside the Capitol, but said the suspect was known to Capitol Police.
"We believe this is an act of a single person, who has frequented the Capitol grounds before," Mr Verderosa said. "There is no reason to believe this is anything more than a criminal act."
Dawson's identity was confirmed by a federal law enforcement official who was not authorised to speak on the investigation.
In October, Dawson reportedly shouted from a House balcony that he was a "prophet of God."
Mr Verderosa said the building's security precautions prevented the suspect from entering the building.
"It appears the screening process worked the way it's supposed to," he said. Police also located and seized the suspect's car on the Capitol grounds, he said.
The shooting briefly shut down the Capitol complex as police told panicked visitors and staff to take immediate shelter and close, lock and stay away from doors.
"Due to police activity, Capitol Police have issued a shelter in place for the Capitol complex. Please stay in your designated area," the Senate sergeant-at-arms said in a tweet during the shutdown.
Gunman caught after shots fired in US capitol
US Capitol Police say a male suspect in a shooting at the visitor's centre is in surgery and that early indications suggest there was no reason to think the incident was more than a criminal act.
Approximately an hour later the Capitol reopened but the visitors centre remained closed, due to reopen for visitors on Tuesday.
Though House and Senate legislators are away on recess, the Capitol remains a popular draw for tourists and school groups visiting in spring at the peak of cherry blossom season.
It comes as the US and Europe step up security measures at airports and public places in the wake of terrorist attacks in Brussels and Paris.
Joe and Leslie Stephenson, visiting from San Diego with their two small children, were at the National Air and Space Museum when they suddenly saw people fleeing the Capitol complex.
"They were out of breath and really shaken up," said Leslie Stephenson, a nurse.
"These kinds of things happen," said Joe Stephenson, who handles information technology for a Southern California police department. He added that the family still hoped to tour the Capitol during their trip. "I don't want to live in fear."
The visitor centre is a vast underground complex beneath the Capitol, where visitors line up for tours. The multi-level space includes a cafeteria, gift shops and official meeting rooms.
Those visiting the Capitol must go through metal-detector screening as they enter the visitor centre, which was built in part as a response to the 1998 shooting deaths of two Capitol police officers who were killed by a man with mental problems. Previously, tourists entered at the same doors used by politicians and staff.
In a separate incident around the same time Monday, the Secret Service temporarily closed the north and south fence lines of the White House after observing a ticketed member of the public attending the annual Easter Egg Roll attempting to move a temporary security barrier, a spokesman said. The incident was separate from what occurred at the Capitol, officials said.
The Secret Service temporarily cleared tourists from an area surrounding the White House after the incident, but activities quickly went back to normal.
The closures were quickly lifted, and pedestrians were again free to walk along the north and south perimeters of the White House grounds.
Cathryn Leff, a licensed therapist, tweeted that she was at the visitor's centre when she heard gunshots while going through a security check point.