Officials say first responders are trying to secure the scene of an active shooter report at a military post near Washington.
Joint Base Andrews, which is about 20 miles outside the nation's capital and is home to Air Force One, said in a tweet Thursday that the base is reacting to the active shooter report to ensure the safety of all personnel.
It was not immediately clear if any shots were fired or if anyone was wounded.
Meanwhile, Homeland Security Secretary Jeh Johnson says there is an "unfolding situation" at Joint Base Andrews in Maryland but is providing no further details.
The base tweeted Thursday morning that it was on lockdown after reports of an active shooter.
JBA is currently on lockdown due to a report of an active shooter. All personnel are directed to shelter in place. More info as it comes.