Eight French nationals, among them three world-renowned athletes, perished in Argentina after two helicopters crashed in the northern part of the country. The athletes were part of a survival-type reality television show and were filming an episode when the helicopters crashed.

The athletes killed include Olympic gold medalist swimmer Camille Muffat, 25; Olympic boxer Alexis Vastine, 28; and renowned sailor Florence Arthaud, 57, according to AFP. The helicopter pilots were Argentine, and the rest of the casualties are French citizens who were working on the TV show.

The show “Dropped” was to air on French television. Its premise is to leave athletes in the wild and having them fend for themselves as they make their way to “civilization.”

The crash happened at the Quebrada del Yeso gorge near the town of Villa Castelli, where the show’s film crew had filmed months prior, in the northern province of La Rioja. Local police provided one of the helicopters, while the other the provincial government provided.

Local spokesperson Horacio Alarcon said weather conditions were suitable, and the cause of the crash remains unknown.

"Apparently, the two helicopters collided as they were filming. There are no survivors," he said.

Other stars of the show, including former soccer player Sylvain Wiltord, swimmer Alain Bernard, cyclist Jeannie Longo, snowboarder Anne-Flore Marxer and figure skater Philippe Candeloro, were not involved in the crash.

Following the news of the crash, France has expressed deep sorrow. According to The New York Times, President Francois Hollande and Prime Minister Manuel Valls expressed their condolences.

“Here again, they wanted to push boundaries and make feats, countries and regions known to the world,” Hollande said.

Adventure Line Productions also released a statement expressing condolences. The company was producing the show and said also that they were filming the second episode at the time of the crash.

Wiltford, a former player with the French national team and Arsenal, tweeted a sad message in which he said, “I am sad for my friends, I am trembling, I am horrified, I have no words. I don’t want to say anything.”

He also posted a black image on Instagram in memoriam of those who died.

The athlete posted a photo of himself with Vastine just weeks before.

The BBC reports the French government has opened a manslaughter investigation into the crash, as its procedure when French nationals die abroad.

Video showing the moment the two helicopters crashed.