An athlete in Sunday's Ironman 70.3 died after needing medical attention during the swim portion, which is the first leg of the event.
Ironman officials said in a statement: "We are deeply saddened to confirm the death of one of our athletes participating in today's Ironman 70.3 Chattanooga triathlon. The athlete required medical attention during the swim and was transported to a nearby hospital where they were treated. Our condolences go out to the athlete's family and friends, whom we will continue to support."
Officials told NewsChannel 9 they would not release the name of the athlete until the family had been notified.
WRCB tweeted that crews pulled a man from the water and performed CPR.
Ironman spokeswoman Ellie Seifert said a death during an Ironman race is uncommon.
"We operate hundreds of events around the world each year and rarely have unfortunate incidents like this one," she said via email.
A Men's Journal article from 2012 looked at the problem of triathletes dying.
According to the article, the odds are one in every 76,000 participants.
But it seems to be the swim portion that can cause the most problems.
A Scientific American article reported:
Despite being the first leg and covering the shortest distance in any triathlon, swimming has proved to be the most deadly. Minneapolis Heart Institute cardiologist Kevin Harris last year published a study in JAMA: The Journal of American Medical Association analyzing the results of 2,971 USA Triathlon-sanctioned events held between January 2006 and September 2008, during which 14 participants died—13 of them while swimming and one while biking. Swimmers who died were between 28 and 65 years old; 11 were men (although it is worth noting that more men compete in triathlons than women).