(CNN) -- A 46-year-old man from Austin, Texas, died Sunday during the swim portion of the Escape from Alcatraz Triathlon in San Francisco, according to race officials.
"We have reason to believe the gentleman suffered from a massive cardiac event as he entered the water and began the swim," race director Bill Burke said in a statement.
"Water safety noticed him immediately and initiated CPR while he was in the water and as they transferred him to land," he added.
Burke said he believes the man's death marks the first in the triathlon's 33-year history.
"The thoughts and prayers of the entire Escape from Alcatraz Triathlon team are with the family and friends of the racer as they mourn this loss," he said.
The statement did not identify the triathlete who died.
The race, which took place in June last year, was scheduled earlier this year to accommodate the 2013 America's Cup. The change in date meant athletes competed in colder conditions.
Approximately 2,000 people take part in the race each year, according to the Escape from Alcatraz Triathlon website. The competition includes a 1.5 mile swim from Alcatraz Island, an 18-mile bike race and an 8-mile run.
Alcatraz Island, in the San Francisco Bay, is known for a high-security prison that operated there for some 30 years before closing in 1963.
Officially, no one ever escaped from Alcatraz, but a handful of prisoners who attempted to escape were never found and remain listed as "missing and presumed drowned," according to the Federal Bureau of Prisons.