Olympic gold medallist Camille Muffat was among 10 killed when two helicopters collided during filming of a reality television show in Argentina on Monday.

The deadly crash occurred outside Villa Castelli in Argentina's La Rioja province during filming for the French reality TV series Dropped.

Retired swimmer Muffat was to be a contestant on the show, a survival-style endurance program with several versions across Europe. She was riding in one of two helicopters when they crashed into one another and "exploded," according to La Rioja government officials, per The Associated Press.

A statement from officials confirmed Muffat was among the 10 dead - eight French citizens and two Argentinean pilots. French Olympic boxer Alexis Vastine, 28, and sailor Florence Arthaud, 57, also died, officials said.

The cause of the crash was not immediately determined.

The broadcaster of Dropped, TF1, released a statement.

"We learn with great sadness the accident on the set of the Dropped show," it read.

"[Chairman] Nonce Paolini and all TF1 teams come together in this terrible time with the pain of the families and relatives of the victims."

Muffat, 25, was an Olympian in 2008 and 2012. 

She won a gold medal in the women's 400 metre freestyle at the 2012 Olympics in London, setting a Games record time. She also won silver and bronze medals that year, before retiring from swimming in July 2014.

Former footballer Sylvain Wiltord, of France and Arsenal fame, tweeted after hearing of the crash: "I'm sad for my friends, I'm trembling, I'm horrified, I have no words, I don't want to say anything."