A firefighter allows a fire engine onto a restricted road leading to Mount Ontake as firefighters head to the mountain to aid in the rescue efforts of those stranded and injured, in Otaki Village, Nagano prefecture, Japan. Mount Ontake in central Japan erupted shortly before noon Saturday, catching mountain climbers by surprise and injuring at least 34, including 12 seriously, according to Japan's Fire and Disaster Management Agency. The tally was lower than reported by local officials earlier, but the disaster agency warned that the numbers could still change. AP Photo
A firefighter allows a fire engine onto a restricted road leading to Mount Ontake as firefighters head to the mountain to aid in the rescue efforts of those stranded and injured, in Otaki Village, Nagano prefecture, Japan. Mount Ontake in central Japan erupted shortly before noon Saturday, catching mountain climbers by surprise and injuring at least 34, including 12 seriously, according to Japan's Fire and Disaster Management Agency. The tally was lower than reported by local officials earlier, but the disaster agency warned that the numbers could still change. AP Photo
A police officer stands guard on a road to Mt. Ontake (top) at Kiso town, in Nagano prefecture, central Japan in this September 28, 2014 photo taken and released by Kyodo. More than 500 Japanese military and police set out on Sunday to search the peak of a volcano popular with hikers a day after its sudden eruption trapped hundreds on the mountain for hours, amid conflicting reports about missing and injured climbers. Mandatory credit. REUTERS/Kyodo
A police officer stands guard on a road to Mt. Ontake (top) at Kiso town, in Nagano prefecture, central Japan in this September 28, 2014 photo taken and released by Kyodo. More than 500 Japanese military and police set out on Sunday to search the peak of a volcano popular with hikers a day after its sudden eruption trapped hundreds on the mountain for hours, amid conflicting reports about missing and injured climbers. Mandatory credit. REUTERS/Kyodo
A man walks next to mountain lodges covered with volcanic ash near a crater of Mt. Ontake, which straddles Nagano and Gifu prefectures in this September 28, 2014 photo taken and released by Kyodo. More than 500 Japanese military and police set out on Sunday to search the peak of a volcano popular with hikers a day after its sudden eruption trapped hundreds on the mountain for hours, amid conflicting reports about missing and injured climbers. Mandatory credit. REUTERS/Kyodo
A man walks next to mountain lodges covered with volcanic ash near a crater of Mt. Ontake, which straddles Nagano and Gifu prefectures in this September 28, 2014 photo taken and released by Kyodo. More than 500 Japanese military and police set out on Sunday to search the peak of a volcano popular with hikers a day after its sudden eruption trapped hundreds on the mountain for hours, amid conflicting reports about missing and injured climbers. Mandatory credit. REUTERS/Kyodo
Firefighters walk down a road headed away from Mount Ontake, background right, as it continues to erupt Sunday, Sept. 28, 2014, in Otaki Village, Nagano prefecture, Japan. Mount Ontake in central Japan erupted shortly before noon Saturday, catching mountain climbers by surprise and injuring at least 34, including 12 seriously, according to Japan's Fire and Disaster Management Agency. The tally was lower than reported by local officials earlier, but the disaster agency warned that the numbers could still change. AP Photo
Firefighters walk down a road headed away from Mount Ontake, background right, as it continues to erupt Sunday, Sept. 28, 2014, in Otaki Village, Nagano prefecture, Japan. Mount Ontake in central Japan erupted shortly before noon Saturday, catching mountain climbers by surprise and injuring at least 34, including 12 seriously, according to Japan's Fire and Disaster Management Agency. The tally was lower than reported by local officials earlier, but the disaster agency warned that the numbers could still change. AP Photo

OTAKI, Japan: Rescuers rushed Sunday to help dozens of hikers stranded on an erupting volcano in central Japan with six people believed to be buried under ash and dozens injured.

Columns of thick white steam were rising from the 3,067-metre (10,121-foot) Mount Ontake, which erupted around noon on Saturday, spewing ash, rocks and steam on otherwise a sunny autumn weekend busy with tourists and hikers.

Seven people were unconscious and buried under ash, national broadcaster NHK said.

One of them was rescued but the others remained on the mountain, NHK said, adding that a total of 42 people were believed to have suffered injuries.

Local media on Saturday reported that a person died, but firefighters said the death had not been confirmed.

A suffocating blanket of ash up to 20 centimetres (eight inches) deep covered a large area of the volcano, trapping climbers and forcing up to 150 to seek refuge in mountaintop shelters at one point.

Local officials believe 45 to 49 hikers sheltered overnight in cabins on the popular mountain, although details remained unclear.

A group of 23 hikers who spent the night in a cabin on Sunday were able to climb down to reach the start of a trail leading to the summit.

A Self Defence Force helicopter rescued a man and a woman near the summit, according to a spokesman at Otaki village, Nagano prefecture.

“The helicopter flew over there very early in the morning to survey the condition. Then it found the two people waving at it,” the spokesman told AFP.

“Originally, the rescuers thought it might be difficult to go near them because ashes could rise (and damage the helicopter), but the conditions were better than they believed and they were able to rescue the two people,” he said.

The two were able to walk unassisted, but were transported to a hospital for observation, the spokesman added.

Some 230 hikers were able to make it to safe ground on Saturday after the eruption.

Ariel television footage showed a line of rescue workers, wearing orange uniforms or green camouflage, scaling grey, ash-covered trails Sunday.

Among the injured, some were hit by flying rocks or suffered burns after inhaling hot volcanic ash, the Yomiuri Shimbun said.

The meteorological agency forecast further eruptions, warning that volcanic debris may settle within four kilometres (2.5 miles) of the peak.

The agency also placed restrictions on access to the mountain, while calling on local residents to remain alert as an eruption could shatter windows miles away.

The last significant eruption of Mount Ontake, which straddles Nagano and Gifu prefectures in the centre of the country, was in 1979 when it expelled more than 200,000 tonnes of ash, according to local media.

A more moderate eruption was last seen in March 2007. -AFP