The US Navy facility which houses the Walter Reed National Military Medical Centre was put on lockdown on Wednesday due to a bomb threat, Naval Support Activity Bethesda officials tweeted.
Personnel in the facility were ordered to shelter in place after receiving phone call from an anonymous number at 8:45 am.
The base previously said that it was investigating an active shooter situation, though this has since been retracted.
K-9 units are now on the scene and are clearing units as the shelter in place remains active.
The Walter Reed National Military Center is known for treating presidents and senior staff, including then-President Donald Trump, who spent time at the facility upon being diagnosed with COVID last year.
This is a breaking story and will be updated.