The helicopters crashed Monday afternoon near Villa Castelli, about 730 miles northwest of Buenos Aires, said La Rioja regional Secretary of Security Cesar Angulo. All aboard -- eight French nationals and two Argentine pilots -- were killed.
Among the dead were Olympic champion swimmer Camille Muffat, Olympic boxer and bronze medalist Alexis Vastine, and pioneering sailor Florence Arthaud. They had been among the contestants in the reality TV show "Dropped."
The bodies were being transported to the regional capital of La Rioja province, where autopsies would be conducted, Judge Virginia Illanes Bordon told television channel Todo Noticias. Illanes Bordon said the rough terrain made recovering the bodies late Monday impossible.
Television images showed investigators pulling cellphones, papers and other charred, unrecognizable items from the wreckage in dry scrubland of a sparsely populated area along the Andes mountain range that separates Argentina and Chile.
The crash was believed to be one of the deadliest incidents related to reality TV shows, a subgenre of which involves taking celebrities and others to far-flung places to face challenges both physical and mental.
French President Francois Hollande expressed "immense sadness" about those who died, and the Paris prosecutor's office opened an investigation into possible involuntary manslaughter, which is to be conducted by a research unit of the French air transport police, a French police official said.
The remaining victims were identified as Laurent Sbasnik, Lucie Mei-Dalby, Volodia Guinard, Brice Guilbert and Edouard Gilles, as well as pilots Juan Carlos Castillo and Roberto Abate.
Cristina Alvarez, the wife of Castillo, told Todo Noticias that her husband was a veteran of the Falklands War and had vast experience flying helicopters, including in places like Antarctica and the Falkland Islands.
Her voice cracking, she said her husband was "extremely happy" because he had recently found out he was going to be a grandfather.
Angulo, the security secretary, said one of the helicopters belonged to La Rioja province and the other to neighboring Santiago del Estero province.
"The helicopter from La Rioja was a Eurocopter with a capacity to hold six people. It appears to have brushed against the other helicopter from Santiago del Estero shortly after takeoff," the statement from the provincial government said.
The crew had arrived Sunday in Villa Castelli, where it had previously filmed a version of "Dropped" for Switzerland and Denmark, said Mayor Andres Navarrete.
French Secretary of State for Sport Thierry Braillard said on the BFM TV channel that "French sport has lost three stars this morning."
Vastine, 28, won a bronze medal at the 2008 Olympic Games in Beijing and lost in the quarterfinals four years later in London amid a sporting controversy that led him to break down in tears. He had reportedly vowed to win gold at the 2016 games in Rio.
Muffat, 25, won gold in the 400-meter freestyle in London plus a silver medal in the 200-meter freestyle and a bronze in the 4 by 200-meter freestyle relay. She had since retired from swimming to focus on her personal life.
But perhaps the best known was Arthaud, 57, a pioneer in sailing. In 1990, she became the first woman to win the famed Route du Rhum race, a trans-Atlantic single-handed yacht race between Brittany and the Caribbean island of Guadeloupe.
Other "Dropped" contestants on hand included former France and Arsenal striker Sylvain Wiltord, ice skating champion Philippe Candeloro, former Olympic swimming champion Alain Bernard and veteran cyclist Jeannie Longo. None of them was involved in the accident.
"I am sad for my friends, I'm trembling, I'm horrified, I don't have words. I can't say anything," Wiltord tweeted.
Candeloro, speaking on RTL radio, said the other contestants were at their hotel Tuesday awaiting arrival of French consular officials.
The deaths are likely to place new attention on risks involved with such shows. Two years ago, TF1 -- France's leading private-sector network, which aired the program -- canceled the season of the "Survivor"-like show "Koh Lanta" after a 25-year-old participant died of a heart attack on the first day of filming in Cambodia.
Show producer Adventure Line Productions was behind both programs. In a statement, the company said its staffers were "devastated" and "share the deep pain of the families and loved ones."
Reality TV shows can appeal to former adrenaline-powered star athletes who often remain famous and beloved long after their careers are over and are looking for new challenges or fun.
William Forgues, Muffat's companion, told i-Tele cable news channel that she was instructed not to reveal details about the show filming but "told everybody that it was great. She was not forced [to do things]. She was where she wanted to be."
"C'est la vie," he added.
French Athletes Die In Helicopter Collision
Three French athletes, including Olympian Camille Muffat, were among 10 people killed in an Argentinian helicopter collision.