An avalanche that struck a school group skiing in the Alps has killed two French high school students and a Ukrainian skier.

Officials say the avalanche in the Deux Alpes resort on Wednesday afternoon hit 10 students from the Saint Exupery school in Lyon and their teacher.

They did not give any information on the number of missing but said 60 rescue workers have been mobilised in a search-and-rescue operation with sniffer dogs and a helicopter.

French police commander Bertrand Host told BFM television that there had been an avalanche warning in the area before the snow slide.

The avalanche struck late today.

The regional Dauphine Libere newspaper is reporting that four students were found in cardiac arrest and the teacher was unconscious.

Venosc mayor Pierre Balme told the paper the avalanche happened on a closed ski run.

French president Francois Hollande has sent his condolences to those close to the victims. In a statement Wednesday evening he said the French education minister is on his way to Lyon. He is expected to arrive in the coming hours to "support the school community and the families".