Updated as of June 30, 10:52 AM - JOINT BASE ANDREWS, Md.— A law enforcement official told the Associated Press officials found no active shooter at Joint Base Andrews Thursday.

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Joint Base Andrews in Maryland has been placed on lockdown following a report of an active shooter.  

The base was placed on lockdown just after 9 a.m. Thursday, officials at the base told News4. All personnel have been directed to shelter in place.

Joint Base Andrews said it had planned an active shooter exercise for 9 a.m., but around the same time, first responders received reports of an "real-world active shooter situation" at the medical facility. The base says it investigating the incident as an ongoing active shooter situation.

Homeland Security Secretary Jeh Johnson called the incident an "unfolding situation" during his testimony at the Senate Judiciary Committee’s hearing on oversight of the Department of Homeland Security.

Some military installations in the D.C. area have increased their security in response to the incident at Joint Base Andrews. 

Fort Belvoir in Fairfax County, Virginia, says it has increased its "security posture", and the Washington Navy Yard in Southwest Washington has ordered "100 percent ID check" and "long guns at entrance gates."

Security has also been heightened at the Naval Observatory in Northwest Washington and the Naval Surface Warfare Center's Carderock Division in Montgomery County, Maryland. 

Joint Base Andrews, in Prince George's County, Maryland, is the home of Air Force One and to other emergency reaction units for the area around the nation's capital.

Vice President Joe Biden was scheduled to fly out of Joint Base Andrews Thursday morning for an event in Ohio, his office confirmed. Biden is currently being held at the Naval Observatory. 

Last month, Joint Base Andrews was placed on lockdown after a woman walked onto the base and claimed she had a bomb.

An Explosive Ordinance Disposal team found the woman had no explosives, and she was apprehended.