A Navy base employee was critically injured in a shark attack Monday near a marina at Naval Support Activity Panama City in Florida, officials said.
Emergency responders were initially dispatched after receiving a 911 call reporting a possible drowning.
When base fire and emergency personnel arrived, they determined the individual had been attacked by a shark, according to Capt. Tristan Oliveria, commanding officer of Naval Support Activity Panama City.
Officials said the employee was believed to have been swimming near the installation's Morale, Welfare and Recreation marina when the attack occurred.
The victim is reportedly a civilian employee with the Naval Surface Warfare Center who was swimming during his lunch break, according to the local ABC affiliate WMBB-TV.
First responders provided medical aid at the scene before transporting the victim to HCA Florida Gulf Coast Hospital for treatment.
Several people who were nearby assisted emergency personnel and helped render aid to the injured employee, officials said.
Authorities have not released the victim's identity, age or details about the injuries, citing privacy concerns and the ongoing investigation.
Oliveria said the employee was in critical condition when taken to the hospital.
Officials have not identified the species of shark involved in the attack.
The incident remains under investigation, and additional information will be released as it becomes available.
ABC News' Jason Volack contributed to this report.