Gold Medalist Dies in Boating Accident
PHOTO: Andrew Simpson, an Olympic gold medalist from Great Britain, has died after the Artemis Racing AC72 catamaran capsized during training in San Francisco Bay, May 9, 2013.

A decorated British Olympic sailor died after a Swedish catamaran capsized while practicing for the upcoming America's Cup in San Francisco Bay.

The crew on board the massive catamaran was on a training run near Alcatraz Thursday when the 72-foot boat flipped, landing on its side trapping two-time Olympic medalist Andrew "Bart" Simpson.

Simpson, 36, a father of three, was freed from under the catamaran by rescue crews but died later on despite efforts to revive him.

The Swedish team Artemis was sailing the catamaran when it overturned between 12:30 p.m. and 1 p.m. local time, according to America's Cup officials.

Crew members jumped off the boat and swam toward support boats as the racing boat capsized, although officials said they were still not certain why it tipped over.

Coast Guard rescue teams and a helicopter quickly convened and rescued all 12 sailors from the boat. Simpson was pulled out from under the wreckage.

"The person apparently was submerged for approximately 10 minutes," San Francisco Fire Chief Joanne Hayes-White said.

Simpson was flown to a nearby hospital where he later died.

"It's a shocking experience to go through and we have a lot to deal with," CEO of Artemis Racing Paul Cayard said.

Simpson and his partner Iain Percy won an Olympic gold medal for England in 2008 in the Star class of sailing. The duo was expected to repeat in London in 2012 but was upset by a Swedish team and settled for silver.

The catamaran, which stood nearly 12 stories tall, was sailing in roughly 20-mph wind and officials said the conditions were not dangerous. Even so, experts say catamarans can be sensitive.

"Catamarans have an inherent problem. They're very stable until they're not," sailor Stephan Sowash said.

Thursday's accident was the second in less than a year involving a team training for America's Cup. Last October, a similar boat also capsized during a test run but thankfully no one was injured.

America's Cup runs from July 4 to Aug. 30.

The Associated Press contributed to this report.

More ABC News