Indonesian soldiers and rescuers run after an eruption of Mount Merapi in Argomulyo, Yogyakarta, on Friday. (Trisnadi/Associated Press)

Blistering gas from Indonesia's most volatile volcano spewed farther than expected Friday, incinerating houses at the edge of the danger zone, triggering chaotic evacuations and pushing the death toll above 122.

The injured — with clothes, blankets and even mattresses fused to their skin by the heat — were carried away on stretchers following the first big explosion just before midnight.

Soldiers joined rescue operations in hardest-hit Bronggang, a village 15 kilometres from the crater, pulling at least 78 bodies from homes and streets blanketed by ash up to 30 centimetres deep.

"We're totally overwhelmed here," said Heru Nogroho, a spokesman at the Sardjito hospital, as the number of bodies dropped off at their morgue climbed to 58.

Villager Niti Raharjo, 47, was in the hospital with burn wounds to his legs, alongside his 19-year-old son who suffered burns to his shoulder, hands and legs. Raharjo said a strong tremor woke him up and he grabbed his motorbike and the pair rode away.

"The heat surrounded us and there was white smoke everywhere," he said. "I saw people running, screaming in the dark, women so scared they fell unconscious. Everything was in turmoil while an explosion that sounded like it was from a war came along the river … then it got worse as ash and debris rained down.

Villagers carrying their belongings arrive at a temporary shelter at Maguwoharjo Stadium in Yogyakarta. (Beawiharta/Reuters)

When the debris filled the road, they were thrown from the motorbike. "But fear made us get up and get out of the hell, regardless of the burning pain in our feet," he said.

Merapi's booming explosion just after midnight was six times as powerful as its initial blast on Oct. 26 and triggered a panicked evacuation. Men with ash-covered faces streamed down the scorched slopes on motorcycles, followed by truckloads of women and children, many crying.

Officials wearing facemasks barked out orders on bullhorns as rocks and debris rained from the sky.

Up until Friday, the village of Bronggang, home to about 80 families, was considered to be within the safety zone, despite signs that the notoriously unpredictable mountain could be ready to blow.

Mount Merapi, which means "Fire Mountain," has erupted many times in the last century. In 1994, over a period of several days, 60 people were killed, while in 1930, more than a dozen villages were torched, leaving up to 1,300 dead.

With many bodies found in front of houses or littering streets it appeared that many of the villagers died from the searing gas while trying to flee, said Col. Tjiptono, a deputy police chief.

Activity at the mountain forced an airport in nearby Yogyakarta to close Friday because runways were covered in heavy white ash. It was not clear when it would reopen, said Agus Andriyanto, who oversees operations.

Danger zone expanded

Mount Merapi's "danger zone," meanwhile, was extended by five kilometres to 20 kilometres from the crater's smouldering mouth after the new eruption, said Subandrio, a state vulcanologist.

Even scientists from Merapi's monitoring station were told they had to pack up and move down the mountain. They were scrambling to repair four of their five seismographs destroyed by the heavy soot showers.

Despite earlier predictions that dozens of big explosions that followed Merapi's initial Oct. 26 blast would ease pressure building up behind a magma dome, eruptions have been intensifying, baffling experts who have long monitored Merapi.

"I don't want to speculate if there's going to be a bigger eruption," said Syamsu Rizal, a state expert on volcanoes. "But there's no indication at [this] stage that we're going to see it see quiet down at all in the near future."

More than 75,000 people living along Merapi's fertile slopes have been evacuated to crowded emergency shelters, many by force, in the last week. Some return to their villages during lulls in activity, however, to tend to their livestock.

Before Friday, the death toll from Merapi stood at 44, with most dying in the Oct. 26 blast. With the new deaths around the village of Bronggang it climbed to 122, the National Disaster Management Agency said on its website.

Indonesia, a vast archipelago of 235 million people, is prone to earthquakes and volcanoes because it sits along the Pacific "Ring of Fire," a horseshoe-shaped string of faults that line the Pacific Ocean.

The volcano's initial blast occurred less than 24 hours after a towering tsunami slammed into the remote Mentawai islands on the western end of the country, sweeping entire villages to sea and killing at least 428 people.

The tsunami left thousands of people displaced, with many living in government camps.