Authorities have identified the man who died at the start of the swim portion of a California triathlon as a 46-year-old lawyer from Austin, Texas.
The San Francisco Medical Examiner's office says it is investigating the cause of Ross Ehlinger's death on Sunday morning.
"Escape from Alcatraz" organizers speculated Ehlinger died of a heart attack immediately after jumping into the 51-degree waters of the San Francisco Bay.
Several media outlets reported other swimmers had to be plucked from the San Francisco Bay during the 1.5 mile swim. The swimmers battled colder and rougher waters than in previous races, which are usually held in June.
This year's triathlon date was changed to accommodate the America's Cup yachting races in the bay this summer.