By Marty Graham
SAN DIEGO (Reuters) - A security alert was issued at the U.S. Naval Medical Center in San Diego Thursday after a gunman was reported to have been seen inside the main hospital, but no shots were fired, a base spokesman said.
The incident began as the Navy complex posted an advisory on its Facebook page saying an "active shooter" was present at the hospital and advised all personnel and their families to avoid the area, though no gunfire was reported.
Base spokesman Michael Wiener told Reuters that military security were on the scene searching for a possible suspect.
An anonymous caller reported seeing an unidentified man with a firearm on the fourth floor of the hospital's west wing, a nursing ward, prompting shelter-in-place orders to be issued for the hospital, Wiener said.
As of noon (1500 ET), more than four hours after the call came in, there was still no sign of a gunman or gunfire, but security personnel continued to search buildings on the installation, authorities said.
The medical center, about 2 miles (3 km) north of downtown San Diego, includes a 272-bed hospital and staff of more than 6,500 military and civilian professionals. San Diego is home to the U.S. Navy's Pacific Fleet.
An active-shooter situation reported at the facility in January proved to be a false alarm.
(Reporting by Marty Graham in San Diego; Writing and additional reporting by Steve Gorman in Los Angeles; Editing by Andrew Hay)