Olympic Champion Camille Muffat Among French Athletes Killed in Helicopter Tragedy The crash happened during filming for a reality TV show.

 -- Camille Muffat made it look so easy.

The French swimmer won the gold medal at the 2012 Olympics, setting an Olympic record in the 400-meter freestyle.

The medal-winning run was marked by power and efficiency and grace, her limbs slicing through the water with machine-like might. When the race was complete, Muffat stuck out her tongue and hugged her teammate, a defining accomplishment for the then-22-year-old.

The Olympic highlight drew renewed attention Monday after news emerged that Muffat, 25, and seven others perished when their helicopters collided while filming a reality-TV show in northwest Argentina. Other victims included Olympic boxer Alexis Vastine and champion sailor Florence Arthaud.

The sports figures were part of a team filming the reality show "Dropped," a survivalist program with several versions across Europe. News of the deaths sent the French sports world into mourning.

"The brutal demise of our compatriots is an immense sadness," French President Francois Hollande said in a statement.

Muffat’s addition to the TV program was announced about two weeks ago. She had participated in various events and causes since retiring from swimming last year, a retirement she partially attributed to a dispute with her coach.

“I have taken a big decision to stop swimming,” she said in 2014, according to the French newspaper L’Equipe, translated by Agence France-Presse. “[The disagreement with coach Fabrice Pellerin] will stay between us like many other things, good or bad, but I mention that because that was what started things off.”

The helicopters crashed while flying near Villa Castelli in La Rioja province, about 730 miles northwest of Buenos Aires, La Rioja Secretary of Security Cesar Angulo told television station TN. "An explosion occurred and it's believed that they collided," Angulo said.

Photographs showed the burning and smoking wreckage of the helicopters on the ground in dry scrubland with people gathered nearby.

The crew had arrived Sunday in Villa Castelli, where it had previously filmed a version of the show for Switzerland and Denmark, Villa Castelli Mayor Andres Navarrete said.

Both Argentine pilots, identified as Juan Carlos Castillo and Roberto Abate, died in the crash.

"The causes of the crash are not known," Navarrete told radio station Cadena 3.

Following the crash, the show's broadcaster TF1 released a statement.

"We have learned, with great sadness, the accident on the set of the show 'Dropped,'" the statement reads. "[Chief Executive Officer] Nonce Paolini and all TF1 teams come together in this terrible time of pain for the families and relatives of the victims."

Vastine, 28, won a boxing bronze medal at the 2008 games in Beijing in the 60-64 kilogram category, but his semifinal loss to Manuel Felix Diaz was marred in controversy as he was docked points by the referee in the final round. Vastine broke down in tears after the defeat.

Arthaud, 57, won the 1990 Route du Rhum, a prestigious yacht race between Brittany and the Caribbean islands of Guadeloupe, a triumph in the male-dominated sport. Her athletic successes followed a serious car accident at age 17 that left her in a coma.

Fellow swimmers Monday reflected on Muffat’s presence.

"Camille was quite a shy and reserved person. She was discreet. But when it was time for a bit of a laugh she was always there," Olympic gold medalist Amaury Leveaux said. "French sport has lost a great champion."

The Associated Press contributed to this report.