Hundreds of balloonists in New Mexico lifted off Saturday at dawn amid a somber mood, opening the Albuquerque International Balloon Fiesta while search crews on the other side of the globe scoured the seas for two of the sport's most acclaimed pilots.

Richard Abruzzo of Albuquerque and Carol Rymer Davis of Denver were participating in the 54th Gordon Bennett Gas Balloon Race when contact was lost Wednesday morning over the Adriatic Sea. Scuba divers joined in the search efforts Saturday, but race organizers said the two plunged toward the water at 50 mph (80 kph) and likely didn't survive.

Kevin Knapp, a pilot and deputy director of the America's Challenge gas balloon race scheduled to begin Tuesday in Albuquerque, acknowledged that the mood is more serious this year, but he said friends and colleagues of the pair are holding onto any hope.

"To survive a descent like that is challenging. I know people who have, I know people who haven't, but all we know now is that it was a fast descent. We know they're still missing, we know the search is still on and we all still have hope," said Knapp, who described the pair as mentors to many in the ballooning community.

The Italian Coast Guard said a group of eight divers equipped with underwater cameras searched in the Adriatic on Saturday. But spokesman Lt. Massimo Maccheroni said "hopes of finding them alive after four days at sea are close to zero."

Maccheroni did not say when the search would be called off, but said "we are close to the limit."

The fiesta draws hundreds of pilots from around the world and more than 800,000 spectators each year.

Concern about the two could be heard throughout the crowd on Saturday in between sips of hot chocolate and coffee and the cheers that erupted each time one of the colorful balloons lifted off. The newspaper headlines in stands around balloon fiesta park summed it up: "Conflicting Emotions."

Abruzzo's wife, Nancy, said in a statement that "we recognize that we are looking for a needle in a haystack." But, she added, "we cannot rest until we find something, anything."

She said that no "physical evidence from the balloon, the gondola, equipment or personal effects" had been found.

Alan Zielinski, a pilot from Chicago, said Abruzzo and Davis are part of the "brotherhood" of balloonists and are personal friends with many who are participating in the fiesta.

"We're all just hoping and praying, each and every one of us, that we're going to get some good news," he said. "We're watching very vigilantly."

In the Gordon Bennett race, teams compete to fly the farthest on a maximum of about 1,000 cubic meters (35,300 cubic feet) of gas. Abruzzo, 47, and Davis, 65, won the 2004 edition of the Gordon Bennett race and the 2003 America's Challenge gas race _ one of Abruzzo's five victories in that race.

Most gas balloon racers _ including Abruzzo and Davis _ are hobbyists who spend thousands of dollars on the adventure sport. Abruzzo works in a prominent family business in Albuquerque that is involved in real estate and operations of the Sandia Peak tramway, Sandia Ski Area and Ski Santa Fe. Davis is a radiologist who specializes in reading mammograms.

Rear Adm. Salvatore Giuffre, coordinating the search efforts in Bari, said that at 8:15 a.m. Wednesday, "the pilot said in English that they were going down very fast toward the sea."

"Those were the last words he said," Giuffre told APTN. "From then on there has been no radar trace from the board transponder."

Since then, search and rescue teams with the Italian coast guard, the U.S. Navy and Croatian coastal aircraft crews have been scouring the Adriatic Sea.

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Associated Press Writer Alessandra Rizzo in Rome contributed to this report.