At least 10 people were killed when two helicopters collided in mid air in northern Argentina on Monday, according to media reports.The accident occurred, near the town of Villa Castelli (around 1,100 km from Argentina's capital Buenos Aires), in the province of La Rioja."There was a crash (involving) two helicopters. There are 10 confirmed dead," a provincial government spokesman told Efe.Weather conditions were reported to be normal at the time of the accident and the reasons for the collision was yet to be determined.One of the helicopters belonged to the La Rioja provincial government and the other to the government of the neighbouring province of Santiago del Estero, an official told the media.According to the official, the helicopters were in Villa Castelli for the filming of a documentary in the area of Quebrada del Yeso. Nearly all of the dead were French citizens, except one of the helicopter pilots, reports said.