JOINT BASE ANDREWS, Md. (AP) — Joint Base Andrews tweeted Thursday that the base was on lockdown due to a report of an active shooter.

The tweet instructed all personnel at the base in Washington's Maryland suburbs to shelter in place and says more information will be released as it comes.

A second tweet from the base said the incident was ongoing at the Malcolm Grow Medical Facility and first responders were on the scene. It instructed everyone to continue to shelter in place, a precaution meant to keep people safe while remaining indoors.

Joint Base Andrews is located about 20 miles outside of downtown Washington, D.C. and hosts aircraft used by President Obama.