A French official says that some high school students swept away by a deadly avalanche in the Alps may have skied ahead of their teacher.

Jean-Paul Bonnetain, top administrative official for the Isere region, urged all skiers to heed avalanche warnings after three people were killed at the Deux-Alpes ski resort Wednesday. Two were among a group of 10 French high school students skiing with their teacher, and the third was believed to be a Ukrainian skier.

Speaking on i-Tele television Thursday, Bonnetain said "initial witness accounts describe students passing ahead of the leader."

Another regional official said the group had no guide. Gendarmes returned to the scene Thursday to investigate, according to the official, who is not authorized to be publicly named according to administration policy.