British yacht-racing champion Andrew "Bart" Simpson was killed when his vessel capsized in San Francisco Bay during training for the America's Cup.
The 36-year-old Olympian, who won a gold medal at the 2008 Beijing Olympics, was sailing on Thursday on the Artemis when the catamaran overturned, according to a statement posted on the Artemis racing website.
"The entire Artemis Racing team is devastated by what happened," CEO Paul Cayard said in the statement. "Our heartfelt condolences are with Andrew's wife and family."
Al Jazeera's Richard Martin said Simpson, who recently won a silver medal at the 2012 London Olympics, was a strategist for the sailing team.
He added that rescuers freed him in 10 minutes but were unable to revive him. The 11-member crew on board are safe and accounted for.
The twin-hulled boat, Sweden's entry in the America's Cup, was performing a so-called "bear-away" maneuver, turning away from the wind, when one bow dropped under the water's surface and the vessel flipped over, America's Cup spokesman Tim Jeffery told Reuters.
The yacht was "very badly damaged," but the team has a backup boat that is expected to be ready to sail in June, he said.
The incident was believed to be the first fatality in connection with the America's Cup since the early 1990s, when a crew member from a Spanish team died in a training accident off the coast of Majorca in the Mediterranean, Jeffery said.
San Francisco Fire Department spokeswoman Mindy Talmadge said one other sailor from the Artemis was taken to a hospital with minor injuries and later released.
Although America's Cup vessels sail with 11 crew members when they race, they are known to carry one or two more or one or two fewer members on practice runs.
Martin said that Simpson was sailing on an AC72 catamaran. The same model, belonging to a different team, capsized seven months ago not too far from the accident.
Winds on Thursday were blowing on the water at 18 to 20 knots, which race organizers described as typical for the bay.
"The boats are designed to sail and compete in winds of up to 30 knots ... so this wasn't excessive," one America's Cup official told Reuters. "It was windy but not super-extreme."
The wreck of the Artemis was at least the fourth major accident in just over a year off the California coast or involving California vessels.
In March a crew member was killed when a 30-foot (9-metre) sailboat broke apart in rough seas during a race near San Clemente Island.
In April 2012 four crewmen in a race from Southern California to Mexico died after their yacht ran aground. Two weeks earlier, five sailors died in a racing accident near the Farallon Islands off the coast of San Francisco.
The Farallon incident prompted the Coast Guard to temporarily suspend racing in the Pacific Ocean off northern California.
This year's America's Cup competition begins in July with qualifying races known as the Louis Vuitton Cup. The America's Cup contest itself is slated to start on September 7. All the races will be run on San Francisco Bay.