Two men are missing and feared unconscious on a 2,100-meter-high mountain slope in central Japan's Nagano Prefecture after they were caught in an avalanche while backcountry skiing Sunday afternoon, local police said.

Police are set to begin their search after 7 a.m. Monday as weather conditions and other factors have made immediately commencing the search unviable. The avalanche occurred at around 2:30 p.m. in backcountry terrain outside of the skiing courses of Tsugaike Mountain Resort in the village of Otari.

Photo taken on Jan. 29, 2023, shows Tsugaike Mountain Resort in Otari, Nagano Prefecture in central Japan. (Kyodo)

Three other skiers hit by the avalanche were among 11 foreign nationals who have already descended from the mountain, according to police. Nine made the journey on foot, while the remaining two, including one who broke an arm, used a snowmobile.

A total of 13 people of three groups, all foreign nationals, were backcountry skiing at the time of the avalanche, the police said.

An avalanche warning had been issued for the northern Nagano region, including the village.

The police were alerted by a foreign skier who witnessed the snowslide, which occurred on the eastern slope of 2,469-meter Mt. Hakuba Norikura near the border with Niigata Prefecture.

People injured (behind a blue sheet) get into an ambulance at Tsugaike Mountain Resort in Otari, Nagano Prefecture in central Japan. (Kyodo)

According to the Japan Meteorological Agency, the region had witnessed heavy snowfall over the past few days, and the accumulated snow had reached 103 centimeters as of 3 p.m. Sunday, compared with 77 cm on Friday night.

It means there was a risk of "surface avalanches," in which a layer of fresh snow slides down, an agency official said.

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