At least four people died in avalanches in the mountains of Japan this weekend after heavy snowfall and high winds raised danger levels. The dead included two Japanese nationals and two Argentine men, according to the police.

The Argentine men, 54 and 50 years old, were skiing Sunday in the backcountry near Ryuoo Ski Park in Nagano prefecture, about 200 kilometers northwest of Tokyo, when an avalanche occurred at around 2:30 p.m.

The two were located by the ski patrol but were pronounced dead at a local hospital, a spokesman at Nagano Prefectural Police told Japan Real Time. They were staying at the resort with three other tourists, from New Zealand and Australia. Public broadcaster NHK reported that the avalanche was approximately 30 meters wide and 200 meters long.

Also over the weekend, two Japanese men died in separate avalanches near Myoko in Niigata Prefecture, the police said. One of them, 35 years old, had been skiing beyond the resort boundaries, but the other death, involving a 48-year-old man, occurred on a marked, patrolled ski run, according to the Niigata Prefectural Police.

The Nagano police also said three climbers remained missing Monday in Japan’s Northern Alps.

Avalanche deaths occur from time to time in Japan, though less regularly than in the European Alps. The number of incidents this weekend was unusual, and followed an exceptionally snowy start to the ski season.

In some areas more than a meter of new snow was reported since Friday, accompanied by winds that gusted to more than 100 kilometers per hour. High winds can whip snow into unstable cornices and slabs that break when a skier passes over them, causing avalanches.

Nagano police warn on their website that there have been multiple cases in recent years in which skiers and snowboarders were swept up in avalanches because they were in no-entry areas.

More skiers have been venturing into these areas in recent years as Japanese resorts relax restrictions on backcountry skiing. The popularity of snowboarding and the use of wider skis have made deep powder more accessible.

Three Japanese snowboarders got lost in the mountains for two days earlier this month after they ventured beyond the boundaries of Kagura, another Niigata prefecture ski resort. They were later rescued with minor injuries.

–Eric Pfanner contributed to this article.

Corrections & Amplifications

An earlier version of this post included a reference to an avalanche in which three skiers were rescued near the Niseko ski resort on Japan's northern island of Hokkaido. That rescue occurred in January 2014. The earlier version incorrectly said it occurred on Jan. 17, 2015.