UPDATE 3:06PM
Despite numerous media reports within the past few minutes, Naval Support Staff at the Walter Reed Medical Center in Bethesda, Maryland say there are "no signs of an active shooter" at the complex.
Officials add to "be aware that all gates are closed until further notice." NBC 4 in Washington reports police say they have yet to confirm an active shooter. Maryland Congressman Dutch Ruppersberger tweeted that he is at the medical center and is safe in a conference room with 40 others.