Tokyo, Jan 29 (IANS): Several people were found unconscious after an avalanche hit a ski resort in Japan's Nagano prefecture on Sunday, local media reported.

The accident took place around 2:30 p.m. local time (0530 GMT) in the backcountry area outside the course of Tsugaike Kogen Ski Resort, Xinhua News Agency reported quoting local police.

The accident site is on a slope eastside of Mount Norikura, at an altitude of more than 2,100 meters, the country's public broadcaster NHK reported.

Several snowboarders were involved, with the exact number of people involved and their degree of injury remaining unknown, reported NHK, citing local police and firefighters.

According to the Japan Meteorological Agency, there was almost no snow in the northern part of Nagano prefecture during the day, but the depth of snowfall in Otari village reached 103 centimeters as of 3 p.m. local time, NHK reported.

The weather agency also issued an avalanche warning for Nagano prefecture due to the sudden increase in heavy snowfall after January 24.