HONOLULU — All six crew members aboard a B-52 bomber that crashed off Guam were killed, the Air Force said Wednesday.

A wide search effort has shifted focus from rescue to recovery of the crew and pieces of the wreckage. Two bodies have been found; the Air Force, without elaborating, said in a news release that forensic specialists were trying to identify additional remains recovered.

"Losing this bomber crew has been a tragedy felt by everyone here and across the Air Force," said Brig. Gen. Doug Owens, commander of the 36th Wing.

The six crew members were identified as Maj. Christopher M. Cooper, 33, aircraft commander; Maj. Brent D. Williams, 37, navigator; Capt. Michael K. Dodson, 31, co-pilot; 1st Lt. Joshua D. Shepherd, 25, navigator; 1st Lt. Robert D. Gerren, 32, electronic warfare officer; and Col. George Martin, 51, flight surgeon.

Martin, also was the deputy commander of 36th Medical Group at Andersen Air Force Base.

"Our thoughts and prayers continue to be with the families of these airmen," said Col. Robert Wheeler, 2d Bomb Wing commander. "We appreciate the military and civilian organizations who are continuing recovery efforts to bring our airmen home."

A panel of Air Force officers is investigating the crash.

With ideal conditions, the Coast Guard, Navy, Air Force, National Guard and local agencies scoured more than 7,000 square miles of the Pacific in three days before suspending the search for survivors.

"It's extremely difficult to suspend this search," said Capt. Thomas Sparks, commanding officer of the Coast Guard's Sector Guam. "Our hearts go out to the families of the victims and the entire Coast Guard grieves for their loss."

The B-52 was carrying nearly 19,000 gallons of jet fuel when it crashed but the National Oceanic Atmospheric Association determined there was no threat to the environment because all or most of the fuel had burned, the Coast Guard said.

The unarmed bomber crashed Monday during a swing around the island as part of Guam Liberation Day celebrations, marking the day when the U.S. military arrived to retake control of the island from Japan during World War II. The B-52 had been scheduled to conduct a flyover in a parade.

The crew was based at Barksdale Air Force Base in Louisiana. Flags were being flown at half-staff at the Louisiana state Capitol to honor them. They were deployed to Guam with the 20th Expeditionary Bomb Squadron as part of the U.S. military's continuous bomber presence mission in the Pacific.

The B-52 has been the backbone of the U.S. military's manned strategic bomber force for more than four decades, used for missions from attacks to ocean surveillance. It's capable of dropping or launching the widest array of weapons in the U.S. inventory, including cluster bombs and precision guided missiles.

B-52s were first placed into service in 1955, and 93 remain in the Air Force's fleet.

The Air Force has been rotating B-1, B-2 and B-52 bombers through Guam since 2004 to boost the U.S. security presence in the Asia-Pacific region while other U.S. forces in the area have been sent to the Middle East.

Monday's crash is the third for the military this year on Guam, a U.S. territory 3,700 miles southwest of Hawai'i.

A Navy EA-6B Prowler electronic warfare aircraft crashed into the ocean Feb. 12. Four crew members ejected from the aircraft and were rescued by helicopter.

Eleven days later, an Air Force B-2 crashed at Andersen shortly after takeoff in the first-ever crash of a stealth bomber. Both pilots ejected safely. The military estimated the cost of the loss of the aircraft at $1.4 billion.

The Air Force's last crash involving a B-52 was also to perform for spectators.

On June 24, 1994, a bomber was practicing touch-and-go landings before an air show at Fairchild Air Force Base in Washington state when it plunged to the ground and exploded, killing all four on board.