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The base was given the all-clear by 3:20 p.m. EST.
Despite the assurance by military officials that it was a drill, a congressman who was on the base was sheltering in place and may not have known that. Maryland Congressman Dutch Ruppersberger was in a conference room with about 40 others taking shelter.
Shortly before the drill was confirmed by multiple media outlets, his representatives tweeted that he didn’t believe it was a drill.
Others posted video of the law enforcement response during the event.