Story highlights Guardsmen aboard were based in Louisiana

Four National Guard aircrew members and seven Marines were aboard the helicopter

Crash happened Tuesday in foggy conditions, which hampered initial search

(CNN) All 11 service members aboard an Army Black Hawk helicopter that crashed in waters off the Florida Panhandle two days ago are believed dead, and the operation has transitioned from rescue to recovery, an Air Force official said Thursday.

The military is now focused on recovering the helicopter, which searchers found at the bottom of the Santa Rosa Sound near Eglin Air Force Base, and the bodies of all seven Marines and four Louisiana Army National Guard members who were aboard, Air Force Col. Monte Cannon said.

Also ahead: Trying to determine why the aircraft went down in thick fog during a training mission Tuesday, Cannon said.

"The decision to suspend is always difficult," said Layne Carter, search and rescue mission coordinator of the U.S. Coast Guard. "With heavy hearts, we have decided to suspend active search and rescue operations. Our thoughts and prayers are with the friends and family of the members involved in this tragedy."

The bodies of at least two National Guard members were recovered Thursday, and the remains of the other two were believed to be in the underwater wreckage 25 feet below the surface, the Guard said. The troops were with 1-244th Assault Helicopter Battalion from Hammond, Louisiana, according to a statement from the Louisiana National Guard.

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