(REUTERS) - Investigators are combing through the debris of a helicopter crash in Argentina that left 10 people dead, looking for clues as to what happened.

Two helicopters, which were filming a reality TV show, collided on March 9, 2015. Among the dead are three French sports stars - Olympic swimmer Camille Muffat, yachtswoman Florence Arthaud and Olympic boxer Alexis Vastine.

"The ten cadavers have been sent to the capital city for the appropriate autopsies to be performed," said Ms Virginia Illanes Bordon, the judge in charge of the investigaion.

Authorities say it is still unclear what caused the accident, saying it is too early to determine if human error, mechanical failure or something else is to blame.

Two French investigators, as well as two technical experts, were dispatched to Argentina to help gather evidence.