TOKYO — Finally reaching the ash-covered summit of a still-erupting volcano in central Japan, rescue workers made a grim discovery Sunday: 31 apparently dead people, some reportedly buried in knee-deep ash.
Four victims were brought down and confirmed dead, one day after Mount Ontake's big initial eruption, said Takehiko Furukoshi, a Nagano prefecture crisis-management official. The 27 others were listed as having heart and lung failure, the customary way for Japanese authorities to describe a body until police doctors can examine it.
Officials provided no details on how they may have died.
It was the first fatal eruption in modern times at 3,067-meter (10,062-foot) Mount Ontake, a popular climbing destination about 210 kilometers (130 miles) west of Tokyo on the main Japanese island of Honshu. A similar eruption occurred in 1979, but no one died.
Rescue helicopters hovered over ash-covered mountain lodges and vast landscapes that looked a ghostly gray, like the surface of the moon, devoid of nearly all color but the bright orange of rescue workers' jumpsuits.
Japanese media reported that some of the bodies were found in a lodge near the summit and that others were buried in ash up to 50 centimeters (20 inches) deep. Police said only two of the four confirmed dead had been identified. Both were men, ages 23 and 45.
Mount Ontake erupted shortly before noon at perhaps the worst possible time, with at least 250 people taking advantage of a beautiful fall Saturday to go for a hike. The blast spewed large white plumes of gas and ash high into the sky, blotted out the midday sun and blanketed the surrounding area in ash.
Hundreds were initially trapped on the slopes, though most made their way down by Saturday night.
About 40 people who were stranded overnight came down on Sunday. Many were injured, and some had to be rescued by helicopters or carried down on stretchers. By nightfall, all the injured had been brought down, officials said.
Japan's Fire and Disaster Management Agency tallied 37 injured people and said it was trying to update the number still missing.
Furukoshi said rescuers gave priority to helping the survivors come down, leaving behind those who were obviously without hope.
Survivors told Japanese media that they were pelted by rocks. One woman said she covered her head with a knapsack, and later found a thermos inside had been flattened.
A man said he and others went into the basement of a lodge, fearing that the rocks would penetrate the roof. He covered himself with a futon, a thin Japanese mattress, for protection.
"Even small eruptions can cause major damage if people are around, as they get hit by rocks that come flying," Nagoya University volcanologist Koshun Yamaoka said at a news conference Sunday. "And the problem is that catching signs of such small eruptions is difficult."
Volcanoes can also kill by spewing toxic gases and lung-choking ash.
Military helicopters plucked seven people off the mountainside earlier Sunday in three helicopter trips, said Defense Ministry official Toshihiko Muraki. All were conscious and could walk, he said.
Japanese television footage showed a soldier descending from a large camouflage-colored helicopter and helping latch on to a man. Then the two of them were pulled up.
At least one woman was carried down on a stretcher, and a man with a broken arm walked down.
The Self-Defense Force, as Japan's military is called, sent seven helicopters and 250 troops. Police and fire departments also joined the rescue effort.
A large white-and-gray plume continued to rise from Mount Ontake, visible from the nearby village of Otaki.
Shinichi Shimohara, who works at a shrine at the foot of the mountain, said he was on his way up Saturday morning when he heard a loud noise that sounded like strong winds followed by "thunder" as the volcano erupted.
"For a while I heard thunder pounding a number of times," he said. "Soon after, some climbers started descending. They were all covered with ash, completely white. I thought to myself: This must be really serious."
Associated Press videojournalist Emily Wang in Otaki, Japan, and writer Ken Moritsugu in Tokyo contributed to this report.