An active shooter was reported at a building at the Naval Medical Center in San Diego, prompting a lockdown, authorities reported Tuesday.

According to the Washington Post, the medical center posted on its Facebook page shortly after 8 a.m. local time that an active shooter had been reported in a building at the facility.

"All occupants are advised to run, hide or fight," the message stated.

The Navy said in a statement a little more than an hour later that according to a single witness, "three shots were reportedly heard" from the basement of Building 26, which houses barracks and a gym.

Officials responded to the scene and are clearing Building 26, the statement said. As a result, the medical center remains locked down and a shelter in place order was given.

Source: MENA