Lock, 58, said they have had drills for events like this, so she didn't panic. "I am now safe in a conference room w/ approx 40 others", Ruppersberger tweeted out.
A mass notification error led to reports of an active shooter Tuesday at Walter Reed National Military Medical Center outside Washington, the U.S. Navy said. The agency instructed individuals at the facility and nearby to await its all clear before entering or moving from shelter.
The Walter Reed National Military Medical Center is seen on May 14 in Bethesda, Maryland. A source told ABC News, "This was in fact an exercise and someone forgot to indicate it was an exercise on the radio, so some people mistook it for an actual threat and initiated proper processes".
Shortly after 3 p.m., another tweet came from Ruppersberger's account, this time written in third-person, saying the congressman "remains sheltered in a back room" and had described his mood as "calm".More news: Fernando Alonso bids 'special' F1 farewell ahead of his hardest challenge
Jeremy Brooks, a Naval Support spokesman, said someone reported an active shooter was in the basement of the building. Authorities have cleared the hospital's basement and are now sweeping the remaining areas of the building.
Walter Reed National Military Medical Center is in Bethesda, Maryland, just outside of Washington.
NSA Bethesda tweeted at 2:15 p.m. that an active shooter had been reported in the basement of a building. Law enforcement, like the Montgomery County Police, treated the situation as a real active shooter scenario and closed down the hospital.
1455, UPDATE: Base security has cleared the basement of Bldg. The entirety of the medical campus was placed on lockdown, with no one allowed in or out until the facility had been cleared.