(PRINCE GEORGE’S COUNTY) — A pre-scheduled drill at Joint Base Andrews in Prince George's County, Maryland, prompted a lockdown Thursday morning after someone saw the armed drill and called authorities, a law enforcement source said.
"The base was scheduled to conduct an active shooter exercise, however, reports of a real-world active shooter situation were reported at Malcolm Grow medical facility," the base said.
The lockdown has now been lifted.
Earlier, all personnel at the base had been told to shelter in place.
Vice President Joe Biden was expected to leave from the base Thursday for Ohio.
The U.S. military facility, located about 17 miles outside of Washington, D.C., is home to Air Force One.
Copyright © 2016, ABC Radio. All rights reserved.