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A spokesman for the Navy Yard in Washington DC said there were no casualties and that no shooter had been spotted at the location.
It followed a decision to put the military installation into lockdown after reports of an active shooter.
There is heightened security in the US ahead of the country’s independence day holiday weekend.
The Navy Yard, a military installation in the American capital, is the site of a 2013 shooting in which a gunman killed 12 people.