(NECN/NBC News: Steve Handelsman) - At least 13 people are dead following Monday morning's shooting spree at Washington, D.C.'s Navy Yard.
Several others were injured in the melee.
The gunman, identified as military contract worker Aaron Alexis, 34, is among the dead.
The U.S. Senate and other office buildings on the Capitol grounds have been locked down as a precaution.
Investigators say reports of two other possible gunmen were false; both of those men have been identified and cleared of any involvement.
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