BALTIMORE _ U.S. Rep. Dutch Ruppersberger was among those who sheltered in place at Walter Reed National Military Medical Center in Bethesda, Md., when reports of an active shooter sent the facility into a lockdown on Tuesday afternoon.
However, a spokesman for the Naval Support Activity Bethesda, which handles base operational support at the hospital, said security personnel had not found any evidence of a shooter _ and an "all clear" was given at about 3:20 p.m.
Walter Reed is the nation's largest joint military medical center, and provides care to soldiers wounded in conflicts overseas.
The U.S. Navy and a Department of Defense spokeswoman later said that the incident was a "drill," without providing an explanation. But Naval Support said they had received a call about an active shooter that it described as "a false alarm and not part of a scheduled drill."
Ruppersberger, D-Md., said he was not aware the incident was a drill as he was sheltering in a back room.
Ruppersberger tweeted about 2:30 p.m. that he and others at the military hospital had been told there is an active shooter, and that he was "currently safe in a conference room (with approximately) 40 others."
A Montgomery County Police spokeswoman confirmed officers received a call at 2:27 p.m. reporting a possible active shooter at Walter Reed, and responded to the scene in a "support and assist" capacity.
The Naval Support Activity Bethesda said at 2:55 p.m. that base security had cleared the basement of a building where the report of an active shooter had originated.
It had previously told everyone on the installation to "go to the nearest available vehicle, structure, or building that provides a measure of protection and lockdown."
Jeremy Brooks, a Naval Support spokesman, said someone reported an active shooter was in the basement of the building.
Jaime Lennon, Ruppersberger's spokeswoman, confirmed that Ruppersberger was at the facility for a personal medical appointment.
Lennon said she had exchanged text messages with the congressman during the incident, and that he had told her that he and a group of others had been pulled into a conference room but had been given very little information.
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."
The tweet said the congressman has "not been given any additional details but does not believe this to be a drill."
Just after 3:30 p.m., another tweet came from the congressman: "We've been given the all clear at Walter Reed _ at no point was there any indication that this was a drill."
