Tokyo: Several people were unconscious after being involved in an avalanche on Sunday at a ski resort in Otari village of Japan's Nagano prefecture, the country's public broadcaster NHK 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, according to local police.

The accident site is on a slope eastside of Mount Norikura, at an altitude of more than 2,100 meters, said the report.

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 Jan. 24.

(With UNI/Xinhua inputs)