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Building 26 is shown at the Naval Medical Center in San Diego, California Jan. 26, 2016, during an active shooter attack. Another active shooter was reported at the U.S. Naval Medical Center in San Diego Thursday. Reuters

UPDATE: 2:00 p.m. EDT – Investigators were still looking into an anonymous report of an armed person on the Naval Medical Center in San Diego Thursday.

The case could be the second false alarm in three months at the facility after reports of an active shooter in January. Spokesman Brian O'Rourke said the police response to Thursday’s report was less intense than in January when a person at the facility reported hearing gun shots.

"We are well trained, we know exactly what we're doing. Last time I was inside and we couldn't go anywhere... It's a little scary but we're tough. We're trained," hospital worker Marianna Desimona told the San Diego Union-Tribune.

Naval officials said last month that 11 bomb threats had been made since November against the San Diego Naval Base and BAE shipyards.

UPDATE: 12:58 p.m. EDT — Investigators were searching the Naval Medical Center in San Diego Thursday after receiving an anonymous report of an armed man at the facility. No person with a gun had been found.

"Investigators have thoroughly searched the building and not found anything yet," spokesman Brian O'Rourke said, the San Diego Union Tribune reported. "They are going floor by floor, it's not a quick operation."

O'Rourke said officials from the Department of Defense, the Naval Criminal Investigative Service and San Diego police were taking part in the investigation.

The facility faced a similar situation in January after a false report of an active shooter was received.

UPDATE: 12:40 p.m. EDT — Reports of two active shooters at Fort Gordon in Augusta, Georgia, were part of a planned exercise, officials told local station WRDW Thursday. They said there was no active shooter at the U.S. Army facility.

WRDW reported there was training planned at the facility Thursday.

UDPATE: 12:25 p.m. EDT — The San Diego Unified School District tweeted Thursday that none of its schools were under lockdown due to the shelter in place ordered at the San Diego Naval Medical Center. An anonymous caller reported an armed man at the facility. Officials were investigating the report.

UPDATE: 12:08 p.m. EDT – The Fort Gordon U.S. army facility in Augusta, Georgia, said it was on lockdown Thursday in a Facebook post. Gates at the facility have been closed due to an investigation of an “alleged incident.” No further details were provided.

Local TV station WRDW reported there was training planned at the facility Thursday and it was possible someone reported the drill after hearing shooting and explosions.

UPDATE: 11:59 a.m. EDT – The Naval Medical Center in San Diego remained on lock down Thursday as police teams with dogs investigated an anonymous call reporting an armed man. The call matched a report of a patient at the facility with a weapon, USA Today reported, citing an unnamed official. The official said security personnel found a bullet on the ground at one of the facility’s buildings.

UPDATE: 11:20 a.m. EDT – Personnel at the Naval Medical Center in San Diego were ordered to shelter in place Thursday after an armed man was reported on the premises. An investigation was underway, but a Navy media relations officer told NBC’s San Diego affiliate, KNSD-TV, there was no active shooter at the facility. He said an anonymous call was received at 7:35 a.m. local time reporting an armed man at the facility.

Staff, patients and officials were told not to come to the hospital until the situation has been cleared. The center has a staff of over 6,500 personnel, both military and civilian, and provides medical care to service members and their families, according to its website.

Brian O'Rourke, media relations officer for Navy Region Southwest, told KNSD-TV the naval facility had ordered all staff to remain on alert as a precaution. He said there was not an active shooter. Vehicles were being turned away from the base during the investigation.

Original story: An armed man was reported Thursday on the U.S. Naval Medical Center in San Diego (NMCSD).

“No shots have been fired. Security is investigating. As a measure of precaution staff are sheltering in place — staff and patients en route to NMCSD are advised not to come to the hospital until the scene is cleared,” said an official Facebook post from the Naval Medical Center San Diego.

A media affairs spokesperson for the U.S. military's recruiting station in San Diego declined to elaborate on the situation.

There were reports of an active shooter at the Naval Medical Center in January that were later determined to be a false alarm. Investigators said they could not substantiate that gunshots had been fired.

"The intensive and thorough search of Building 26, as well as the grounds and additional buildings on the grounds of NMCSD, did not reveal anything unusual after the initial witness report was made," the Navy said, CNN reported in January.

Check back for developments.