Two-time Olympic triathlete Laurent Vidal has died aged 31, sports officials said.
The International Triathlete Union said Vidal died "peacefully in his sleep" in his home country of France. There was no immediate indication of cause of death.
Vidal — who competed at the Beijing and London Olympic Games — was a "multi-time" World Triathlon Series & World Cup medalist, according to the International Triathlete Union (ITU).
His racing career was cut short after suffering a cardiopulmonary arrest in 2014 while swimming in France.
Vidal then shifted into coaching other triathletes — including his fiancee, Andrea Hewitt, and other top athletes.
"Laurent was an unforgettable presence, touching the lives of anyone who met him with his positive outlook and incredible energy," ITU President Marisol Casado said in a statement. "He was constantly coming up with new ideas to take our sport to the new level, pushing the envelope in everything he did."
Triathlon New Zealand said Vidal's fiancee was with him when he died and is currently with his family in France.
France's Sports Secretary Thierry Braillard sent condolences to Vidal's family and the triathlon world.
"Very sad news for French sports," he said on Twitter.
Vidal's fellow triathletes also quickly took to Twitter to mourn his passing.
"Unbelievable news this morning," wrote French triathlete Vincent Luis. "My friend Laurent Vidal has left us."
"Triathlon won't be the same, " added Non Stanford wrote. "Deeply saddened."