DESTIN, Fla., March 11 (UPI) -- An Army helicopter from Eglin Air Force Base in Florida crashed during a training exercise. Seven Marines and four crew members are presumed dead and some "human remains" have been found.
Base spokeswoman Jasmine Porterfield said Wednesday a "search-and-rescue" operation was still underway.
Base officials said debris was washing ashore from one of two UH-60 Blackhawk helicopters participating in the nighttime exercise. The second helicopter and all the people aboard returned to the base, officials said.
Gen. Martin Dempsey, chairman of the Joint Chiefs of Staff, expressed his condolences.
The crash is "a reminder to us that those who serve put themselves at risk, both in training and in combat," Dempsey said from Washington, D.C. "We will work with the services to ensure that ... their family members will be well cared for."
The cause of the accident is under investigation. The Air Force, Coast Guard and civilian agencies participated in search operations.
There was heavy fog in the area during the time of the crash, but it hasn't been determined whether the weather conditions were a factor, Eglin officials said.
The helicopter was reported missing about 8:30 p.m. Tuesday. The Marines on board were from a special operations regiment out of Camp LeJeune in North Carolina. The helicopters and crew were assigned to the Army National Guard in Hammond, La.