An active gunman has been reported at the Naval Medical Centre San Diego on Tuesday, according to a post on the medical centre's Facebook page.
San Diego police spokesman Travis Easter said police had received a report of a shooter from officials at the medical centre, but that they had not requested any assistance and so no officer had been sent to the scene.
The post on the medical centre’s Facebook page advised occupants to run, hide or fight.
All non-emergency response staff were asked to stay away from the compound.
The shooter was reported in building 26, the post said.
The building houses offices and barracks for wounded sailors and marines, as well as a gym.
First responders and dog units are clearing the building.
The medical centre remains on lockdown and a shelter-in-place order has been given.
The 272-bed, multi-specialty hospital and ambulatory complex is located on about 78 acres in the southeast corner of Balboa Park, about 2.5 miles from the city centre, according to its website.
Centre staff include more than 6,500 military, civilian, contractor and volunteer personnel.
Reuters and PA