British double Olympic sailing medalist Andrew Simpson died Thursday when a Swedish catamaran capsized during America's Cup training on San Francisco Bay, officials said.

Simpson, a 36-year-old father of two boys, was trapped underneath the 72-foot catamaran of Swedish team Artemis for about 10 minutes after it flipped over and efforts to revive him failed. "Our prayers are with Andrew Simpson's family, his wife and kids, and also the rest of my teammates," a shaken Paul Cayard, chief executive of Artemis Racing, said hours after the accident. "It's a shocking experience to go through, and we have a lot to deal with in the next few days in terms of assuring everybody's well-being."

A fleet of rescue boats -- including chase boats from rival teams -- and helicopters went to the aid of the stricken vessel. Once Simpson was freed from the wreckage, rescuers attempted CPR as he was transported to the St. Francis Yacht Club, where paramedics were waiting. "Unfortunately, they ended up pronouncing him dead at the Saint Francis Yacht Club," San Francisco Fire Department spokeswoman Mindy Talmadge told AFP.

Talmadge said she had no information on what caused the boat to capsize, and Cayard did not immediately address that issue. Another sailor suffered injuries that were not thought to be life-threatening, and all 12 aboard had been accounted for, Talmadge said. Artemis Racing spoke of the team's "immense sadness."

"Despite attempts to revive him, by doctors afloat and subsequently ashore, his life was lost," it said. Simpson was an experienced yachtsman, winner of Olympic gold in Beijing in 2008 and Olympic silver in 2012 in the keelboat star class. "Andrew was an immensely popular and respected member of the sailing community, and his two Olympic medals were testament to his talent," America's Cup officials said in a statement posted on their website.

Simpson -- known across the sailing world as "Bart" after the cartoon character -- had moved to San Francisco with wife Leah and sons Freddie and Hamish to train for six months. He had written in March of his excitement, saying the move had been "pretty hectic" but the America's Cup "should be fun".

Simpson's death plunged the British sailing world into mourning. Stephen Park, Olympic Manager for the Royal Yachting Association (RYA), described him as "a fantastic sailor who got the best out of everyone he sailed with".

The yacht involved was an AC72 catamaran, according to the statement, which said the incident occurred between 12:30 pm and 1:00 pm. The AC72 boats developed for the 2013 America's Cup were described by event organizers as "speedsters" powered by 130-foot (39.6-meter) tall wing sails and with the ability to hydrofoil -- essentially rise out of the water to reduce drag.

They can reach top speeds in excess of twice the windspeed, and place strenuous physical demands on crew members. The catamarans have been adopted for the venerable yachting competition this year in a bid to make the event more exciting. The Oracle syndicate, owned by software billionaire Larry Ellison, defeated Switzerland's Alinghi in a trimaran to win the last edition of the America's Cup in 2010.

Oracle's AC72 capsized in spectacular fashion in October on San Francisco Bay, but no one was injured. "Today is a sad day for all of us in the sailing community," the Oracle team said in a statement. "Andrew Simpson was a great person, a terrific sailor, and a good friend to all of our team. Our thoughts are with his family and the entire Artemis team. He will be dearly missed."

The Louis Vuitton Cup to decide a challenger will be held July 4 through September 1, with Artemis scheduled to take on Team New Zealand and Italy's Luna Rossa for the right to take on Oracle for the America's Cup in September.