SAN FRANCISCO -- A man died Sunday morning during the swimming portion of the Escape from Alcatraz Triathlon, race officials said.

The victim, a 46-year-old man from Austin, Texas, may have suffered a heart attack about 7:30 a.m. as he entered the water and started swimming in the 1.5-mile segment, Bill Burke, race director for Escape from Alcatraz, said in a statement.

Race safety officials noticed the man and administered CPR while he was in the water, then transported him to land.

His name was not immediately known.

Officials said it was believed to be the first death to occur during the 33-year-old triathlon.

According to the Escape from Alcatraz Triathlon website, the event includes a 1.5-mile swim from Alcatraz Island to the shores of the St. Francis Yacht Club, an 18-mile bike ride and an 8-mile run through San Francisco's Golden Gate Recreational Area.