A series of avalanches claimed the lives of four skiers and snowboaders over the weekend on mountain slopes in Nagano and Niigata prefectures.

An avalanche Sunday off the designated run at Ryuoo Ski Park in Yamanouchi, Nagano Prefecture, killed two Argentine nationals. One of them was identified as Esparrica Mario Roberto, 50.

According to the ski slope operator, the avalanche occurred several hundred meters from a prepared slope for advanced skiers.

The Nagano Prefectural Police said the 30-meter-wide, 200-meter-long avalanche started when the two Argentines skied off the prepared slope.

They were with three men and women of New Zealand and Australia nationality, but the others were not caught up in the falling snow.

Also Sunday, a 35-year-old graduate student from Nagoya was found buried in snow near a ski slope at Akakura Kanko Resort Ski in Myoko, Niigata Prefecture. The student, Hiroki Okamoto, was flown by helicopter to a hospital, where he was pronounced dead. He had been missing since Saturday.

The Niigata Prefectural Police said he was found about 250 meters off the ski slope. They said he was hit by an avalanche, traces of which were still visible nearby.

Elsewhere in Myoko, two snowboarders were hit by an avalanche Saturday on Mount Awadachi. They were found by the police and airlifted to a hospital. But Hiroshi Mizuno, a 48-year-old businessman from the city of Joetsu, Niigata Prefecture, was confirmed dead. Mizuno appeared to have suffocated in the snow. Businessman Hiroyuki Kurashige, 38, suffered mild frostbite on his fingers and toes.

The Nagano Prefectural Police said Monday three men climbing in the Northern Alps may be missing. They had planned to return from their trek Sunday. The mountaineers were identified as Osamu Iwata, 57, a businessman from Saitama Prefecture; Hayato Ikeda, 59, of Nagoya; and Harushige Yabuta, 66, of Kobe.