A Texas man died while competing in the Escape from Alcatraz Triathlon in San Francisco on Sunday, Comcast SportsNet Bay Area reported.
Race director Bill Burke said in a statement that the 46-year-old man died of a "massive cardiac event" during the swimming portion, which is the first leg of the event that also includes bicycling and running.
A safety team on site began administering CPR to the man in the water and while it was transferring him onto land.
"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," Burke said. "Safety is always our top priority."
It was the first death in the 33-year history of the event.