The Minnesota family of a U.S. Marine says their dreams were “utterly shattered” as the rescue effort in the waters off Hawaii was called off for their 24-year-old son and 11 others now presumed dead aboard two helicopters that failed to return to base.

The search shifted to “recovery and salvage” after a massive five-day effort found no evidence of survivors. A memorial is tentatively planned for Friday at Marine Corps Base Hawaii in Kaneohe Bay. The cause of the crash remains under investigation.

“Our son Sergeant Dillon Semolina’s last breath was taken in his bird (as he would call it) doing what he loved to do last Thursday night,” the family’s GoFundMe page said. “He took great pride in the Marine Corp[s] and his fellow Marines on his flight line were family to him.”

Semolina, 24, was born in Buffalo in Wright County and graduated from Delano High School. He has been stationed in Hawaii.

The family raised nearly $16,000 in four days on the page so Semolina’s parents could travel to Hawaii for the search. Semolina’s parents thanked the friends and family “for your supporting words just when we think we can’t go on, or a funny memory that takes the pain away for a brief second.”

They added, “This community has rallied behind us and has pushed us to be strong. Words aren’t enough!”

The page also mentioned the memorial service “to honor all 12 of these incredible souls,” who “need a place to rest and say a proper goodbye.”

Last Thursday, two CH-53E helicopters carrying six crew members failed to return to their base at Kaneohe Bay following a nighttime training mission. Hours later, a Coast Guard helicopter and C-130 airplane spotted debris 2½ miles off Oahu.

The transport helicopters were part of the 1st Marine Aircraft Wing at Marine Corps Base Hawaii. Known as Super Stallions, they are the U.S. military’s largest helicopter, capable of carrying a light-armored vehicle, 16 tons of cargo or a team of combat-equipped Marines, according to a Marine Corps website.

The crash was near the north shore, but the search area spanned from the western coast of Oahu to the northeast corner of the island.

The Coast Guard initially reported that the choppers had collided, but the Marines said later that it wasn’t yet known if there was a collision and that the cause remains under investigation.

The Marine Corps will strive to discover all of the facts surrounding the crash, said Brig. Gen. Russell Sanborn, commanding general of the 1st Marine Aircraft Wing.

All four life rafts from the helicopters were found, but they were empty. There was no indication that anyone had been on any of the rafts, based on their condition and the lack of personal effects, the Coast Guard said.

Authorities searched for survivors around the clock. The Coast Guard assumes the best-case scenario when considering how long someone in the right equipment and right conditions could survive, Coast Guard Chief Petty Officer Sara Mooers said.

“We err on the side of caution because the last thing that anybody wants is to suspend the search when there’s still a possibility of finding somebody,” she said Monday.

Aircrews wear personal flotation devices with their flight suits and get additional training on top of survival swimming training, the Marines said.

People have been found days or even weeks after getting lost at sea, Mooers said.

The additional missing crew members are:

— Maj. Shawn M. Campbell, 41, College Station, Texas.

— Capt. Brian T. Kennedy, 31, Philadelphia.

— Capt. Kevin T. Roche, 30, St. Louis.

— Capt. Steven R. Torbert, 29, Florence, Ala.

— Sgt. Adam C. Schoeller, 25, Gardners, Penn.

— Sgt. Jeffrey A. Sempler, 22, Woodruff, S.C.

— Sgt. William J. Turner, 25, Florala, Ala.

— Cpl. Matthew R. Drown, 23, Spring, Texas.

__ Cpl. Thomas J. Jardas, 22, Fort Myers, Fla.

— Cpl. Christopher J. Orlando, 23, Hingham, Mass.

— Lance Cpl. Ty L. Hart, 21, Aumsville, Ore.