Reports of an active shooter at Naval Medical Center San Diego (NMCSD) Tuesday morning led to a lengthy lockdown of the military facility, but U.S. Navy officials confirmed no gunman was found and no injuries were reported.

NMCSD was placed on lockdown just after 8 a.m. and people inside were ordered to shelter in place after an unidentifed Department of Defense employee reported hearing three shots fired in the basement of Building 26, which houses a gym and barracks, according to the Navy.

More than two hours later, K9 units were sweeping the military medical center, honing in on Building 26, Brian O'Rourke, PAO Navy Region Southwest said.

Initial searches of Building 26 turned up no evidence of a gunman or shots fired, O'Rourke said.

When Naval Medical Center San Diego wentis treating this as a possible active shooter. All personnel are advised to execute active shooter procedures. Non-emergency response personnel are asked to stay away from the compound. San Diego Police Department and Chula Vista S.W.A.T. are on scene at building #26."

One by one, individual buildings at the Naval hospital were all placed on lockdown, one employee told NBC 7. The front gate to the facility was also locked.

Florida Drive was blocked off to traffic as law enforcement surrounded the area, including California Highway Patrol officers who were seen entering the facility through an emergency room entrance. A steady stream of patrol cars from multiple agencies, including the San Diego Police Department (SDPD) and Chula Vista Police Department (CVPD), could then be seen flowing into the area.

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