Police say they are checking on a report of a single shot fired at Walter Reed National Military Medical Center outside Washington.

Montgomery County police spokeswoman Natasha Plotnikov says a 911 caller reported hearing one shot inside Building 1, the original hospital on the campus in Bethesda, on Thursday morning. She says police are on the scene checking the report.

Local television coverage shows police cars parked by the building and people walking away from the building.

Police tweeted that they have not confirmed the report of a shot, but they are sending additional officers.

Walter Reed officials could not immediately be reached.