Officials say they've seen "no indication" of an active shooter after clearing the basement of a building at Walter Reed National Military Medical Center outside Washington.
Naval Support Activity Bethesda initially tweeted Tuesday afternoon that an active shooter had been reported in the basement of a building at the Maryland base.
About 40 minutes later, NSAB tweeted that base security had cleared the basement was in the process of clearing the rest of the building. Security had found "no indication so far of an active shooter."
NSAB oversees operational support for its major tenants at the base, including Walter Reed.
In a tweet, U.S. Rep. Dutch Ruppersberger of Maryland says he and about 40 other people were in a conference room at the hospital.
