Tokyo: At least 12 people were injured, some critically, when rocks from an erupting volcano rained down on skiers at a mountain resort in central Japan on Tuesday and an avalanche soon after the eruption engulfed about a dozen skiers.

Six of those trapped were members of Japan’s Ground Self Defence Force (SDF) engaged in winter training manoeuvres, Defence Minister Itsunori Onodera said. All were rescued but most were injured, with several suffering fractures.

Japanese media reported that at least 12 people were injured, many apparently hit by volcanic rocks. Two were critically injured and three suffered serious injuries, national broadcaster NHK said.

One person was trapped in the avalanche for some time before being dug out by rescuers, who included SDF members.

Kusatsu-Shirane, a 2,160-metre (7,090 ft) volcano, erupted on Tuesday morning, the Japanese Meteorological Agency (JMA) said. The agency warned that further eruptions could not be ruled out and that rocks could be thrown as far as 2 km (1 mile) from the peak.

Video footage from the top of the resort’s gondola showed black rocks plummeting through the sky and snow billowing up as they struck the ground, followed by a curtain of black smoke.

‘There was this huge boom, and a big plume of totally black smoke rose up,’ one skier told NHK. ‘I had absolutely no idea what had happened.’

A photograph taken at the site and shown on NHK depicted a gondola with a shattered window. At least several of the injuries were due to broken glass.

‘Several other people appeared to be hurt by the stones, which appeared to be around 10 to 20 cm in size,’ another skier told NHK.

The resort temporarily lost power, leaving a number of skiers suspended in gondolas for around half an hour until they resumed moving. Around 80 skiers were awaiting rescue at a hut at the top of the mountain.

It was unclear whether the avalanche was caused by the volcanic activity, but they occurred nearly simultaneously.

The warning level for the peak was raised to 3, meaning that people should not climb the mountain, the JMA said.

Japan has 110 active volcanoes and monitors 47 of them around the clock. In September 2014, 63 people were killed on Mount Ontake, the worst volcanic disaster in Japan for nearly 90 years.