A bullet from the gunman struck a child who was in the area, but the victim did not sustain life-threatening injuries.
Quinn said it wasn’t clear whom the person may have been targeting.
He said: “We’re patrolling this area, and every site we do, 24/7, hardcore. Whether or not it was directed to the President or not, I don’t know, but we will find out.”
At around 3.45pm, the Secret Service evacuated members of the media from the White House’s north lawn to the briefing room.
Witnesses said about five or six gunshots rang out shortly after Vance had passed by.
Washington DC police said it was investigating the scene of the shooting and that area roads would be closed for several hours.
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