A military helicopter carrying Marines crashed off the Florida panhandle coast and it is believed all aboard have perished.

Search crews continue to search the coast for any survivors but debris and remains have already washed up on the shore.

A Sikorsky UH-60 Black Hawk belonging to the Army National Guard and based out of Hammond, Louisiana crashed Tuesday night off the Florida coast near Eglin Air Force Base, the base reported in a statement.

The helicopter was one of two aircraft partaking in an overnight training exercise involving the Marine Special Operations Regiment from Camp Lejeune, North Carolina.

One of the helicopters, carrying seven Marines and four crewmembers, is believed to have crashed and was reported missing at around 8:30 p.m. Search and rescue operations involving the U.S. Coast Guard as well as other agencies began soon after. By 2 a.m., debris had been found, but heavy fog hindered search efforts.

The Eglin AFB statement said the other helicopter returned safely to base. Both Black Hawks were assigned to 1-244th Assault Helicopter Battalion based in Hammond.

CBS and the AP report that a Defense Department official, speaking under condition of anonymity as he is not allowed to comment on the matter, says it is believed the crew and Marines have perished. However, the official statement is that the troops are missing.

According to Reuters, remains have washed ashore but search efforts continue. Yet, heavy fog in the area continues to hinder efforts. Eglin AFB spokesperson Andy Bourland said the helicopter went down over water but it is unknown as of yet if the heavy fog played a role in the accident.

As he spoke in front of Senate Wednesday morning concerning the AUMF, Defense Secretary Ash Carter informed the panel of the crash and expressd his condolences.

Commander of U.S. Marine Corps Forces, Special Operations Command, based at Camp Lejeune, Maj. Gen. Joseph Osterman also released a statement.

"Our thoughts and prayers are with the Marines, soldiers and family members of those involved in this mishap. We are working closely with all parties involved to locate our Marines and the Army aircrew as soon as possible," he said.

The military will refrain from identifying the troops involved until their families are notified, but the crash is currently under investigation.

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