A Swiss air force helicopter crashed on Friday above the resort town of Crans-Montana, in canton Valais. All four occupants of the aircraft are dead.

The Alouette III had left Sion airport early in the afternoon after refuelling, heading back to the military airbase in Payerne, canton Vaud. Local police said the accident happened near Mount Bonvin, about 500 metres from the Plaine-Morte cable car terminal.

The helicopter hit a cable used for transporting anti-avalanche explosives, and caught fire when it hit the ground, according to the air force. The helicopter was completely destroyed in the accident, with only smoking remains visible.

The reasons for the crash remain unknown at this time. The cable is indicated on maps and the weather was perfect according to the military authorities.

The helicopter was being used to help clean up a training ground in the mountains.

The names of the deceased have not been released. The military investigating judge refused to reveal if the victims were soldiers or civilians, as the families had not yet been informed.

This was the 17th time an Alouette III of the Swiss armed forces has been lost in an accident. This type of helicopter, which carries up to seven passengers along with the pilot, has been in service since 1964 and is used for transporting troops and equipment.

Switzerland's worst helicopter accident happened last year in Beuson, when two aircraft collided, killing a pilot and seven Indian tourists.

swissinfo with agencies

In compliance with the JTI standards

More: SWI swissinfo.ch certified by the Journalism Trust Initiative