Police and fire department officials in Nagano Prefecture said an avalanche struck groups of foreigners who had been skiing off regular slopes.

Survivors reportedly told them that at least one person is unconscious and remains at the site.

Police received a call on Sunday afternoon that the avalanche hit off-piste in the Tsugaike Mountain Resort in Otari Village. The disaster site is in the Tenguhara area, some 2,100 meters above sea level on Mount Norikura.

First responders said that most of the affected skiers climbed down the mountain on their own, but one person was sent to a hospital for a broken arm.

Police plan to conduct a search from Monday morning if weather permits.