SAN DIEGO, Calif. — An active shooter reported on the Naval Medical Center San Diego Facebook page sparked a series of lockdowns Tuesday.

After an extensive search of the facility, however, investigators found no evidence of a gunman or shooting, Navy officials confirmed.

Gunfire was reported by a single witness at about 8 a.m., according to a statement from the Navy. That person reported hearing three shots fired in the basement of Building 26, which is a combination gym and barracks.

First responders and Navy working dog units cleared Building 26 before moving one by one to the other buildings making up the center.

After the initial reports of a shooter, the Naval Medical Center San Diego posted the following message to their Facebook page instructing occupants to “run, hide or fight.”

Three schools in the area — San Diego High School, Garfield High School and Roosevelt Middle School — have all been locked down and parents are being asked to stay home until the situation has been resolved, according to WPIX sister station KSWB.

The Naval Medical Center San Diego is made up of 6,500 military and civilian personnel with the mission of providing health care to service members, veterans and their families, according to the facility website.

Navy officials questioned the sole witness of the alleged shooting; it’s still unclear what prompted the report.