A suspect had been shot and was in custody. CNN quoted police as saying that Secret Service officers shot a male suspect.
One person was transported to a local hospital with critical injuries, a spokesman for the District of Colombia Fire and Emergency Medical Services Department said.
U.S. Park Police said the shooting was on West Executive Drive, about a block from the White House.
Larry Samples said he saw a man with a gun walk past a guard fence, ignoring repeated calls from police who asked him to stop. "Not a word , Reuters Reports.
He just carried his gun at his side, holding it like this," he said. Washington Mayor Muriel Bowser said on Twitter she was aware and had been briefed on the White House lockdown situation.
Her public safety team was coordinating with federal partners, she said.
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