TAMPA, Fla. — A salvage barge moved off the Florida Panhandle coast to lift the wreckage of a shattered Black Hawk helicopter from the waters, days after seven Marines and four soldiers were killed when the aircraft crashed in dense fog on a nighttime training mission.

Air Force spokesman Sara Vidoni said the barge arrived about midday Friday to pluck the debris from about 25 feet of water. The salvage operation opened on a day a military leader in North Carolina disclosed that those aboard the aircraft had tried to abort their mission when they decided it was too risky.

Maj. Gen. Joseph Osterman — commander of Marine Corps special operations forces — said the Marines had been flying offshore before Tuesday’s crash to practice rappelling down ropes into the water and then making for land. The same drill had been practiced earlier.

The teams of Marines and Army-piloted choppers made a judgment call on whether conditions were sufficient for the training mission to go ahead, he noted. Then when they were heading out to start the mission, they tried to abort after deciding it was too risky, Osterman said.

The seven Marines were members of the same team that trained together as part of the Marine Special Operations Command, or MARSOC, which totals about 2,500 troops.

Among those killed was 26-year-old Staff Sgt. Andrew Seif, who had been awarded one of the military’s highest honors for heroism only days earlier. He had been commended for his efforts to save a mortally wounded friend in heavy gunfire in Afghanistan. The other Marine victims were identified as: Kerry Kemp, 27; Marcus Bawol, 27, of Warren, Mich.; Capt. Stanford Shaw, III, 31, from Basking Ridge, N.J.; Master Sgt. Thomas Saunders, 33, from Williamsburg, Va.; Staff Sgt. Trevor Blaylock, 29, from Lake Orion, Mich. and Staff Sgt. Liam Flynn, 33, from Queens, N.Y.

Four National Guard soldiers from Louisiana also were killed, though they’ve not yet been publicly identified.