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

The base has instructed all personnel at the base in Washington's Maryland suburbs to continue to shelter in place and stay inside.

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.