Two French Olympians were among 10 people killed after two helicopters collided in mid-air during filming for a reality TV show in northern Argentina.
Camille Muffat, who won an Olympic gold medal in swimming at the London 2012 games, Olympic boxer Alexis Vastine, and champion sailor Florence Arthaud were filming for the series Dropped.
They were in two helicopters flying over mountains near Villa Castelli, in La Rioja province, when the accident took place.
Photographs showed the burning wreckage of the aircraft in dry scrubland with people gathered nearby.
Police said eight French nationals and their two Argentine pilots were killed.
A statement from La Rioja's government confirmed the identities of the three athletes.
Ms Arthaud, 57, was considered one of the best sailors in the world and had won the 1990 Route du Rhum.
Ms Muffat, 25, won gold in the 400-metre freestyle in 2012, along with two other medals.
Mr Vastine, 28, won a bronze medal at the Beijing games in 2008 in the light welterweight category.
Cesar Angulo, secretary of security for the province, told TN television: "An explosion occurred and it's believed that they must have collided.
"Aeronautical experts will have to determine that."
The statement from La Rioja's provincial government added: "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 take-off."
French President Francois Hollande said: "The brutal demise of our compatriots is an immense sadness."
Former Arsenal footballer Sylvain Wiltord, who is reportedly one of the show's contestants but was not in either helicopter, tweeted: "I'm sad for my friends, I'm trembling, I'm horrified, I have no words, I don't want to say anything."
Olympic swimmer Becky Adlington tweeted: "So sad and shocked to wake up to hear the tragic death of Camille Muffat. She was an amazing sportswoman, competitor and lovely person.
"My thoughts go out to not only all her friends and family but to all the family and friends of all the 10 victims. Its an extremely sad day."
TV show Dropped involves sports stars being dropped into inhospitable environments and trying to survive by foraging for food.
The show's producers Adventure Line Productions (ADL) said in a statement: "All the ADL teams are devastated and share the deep pain of the families and loved ones they are in contact with.
"We are in contact with the production teams on site (and) with the French and Argentine authorities. We will give more information as soon as possible."
A cast and crew of around 80 people were in the area to film the series.
Shooting began in February in Ushuaia, at the southern tip of Argentina, before moving north to La Rioja, a remote area on the edge of the Andes mountain range that separates Argentina and Chile.
Police and firefighters were still working to recover bodies from the wreckage of both helicopters.
An official at the scene said: "It's been four hours since the collision and (the wreckage) is still on fire. There's smoke rising from the helicopters."