Clouds of deadly ash, rock fragments and hot gas surged down Mount Merapi's slopes Monday as activity intensified to the highest level since the volcano rumbled back to life weeks ago.

One eruption sent an avalanche of debris and ash rolling more than 2 miles down the mountain's western flank, said Ratdomopurbo, the region's chief vulcanologist, who like many Javanese uses only one name. It was followed by several other huge explosions.

Many people who earlier had refused to leave the danger zone fled in public minivans or trucks. Villages near the peak resembled ghost towns, with only a few men to be seen. Houses, some dusted with ash, were deserted and shops closed.

"I am panicking this time," said Katimi, a mother of three who had taken refuge in a mosque serving as an evacuation point. "Merapi appears angry."

Hospitals and clinics were preparing for the worst.

"We are prepared for some of the things that we may deal with, (from our experience) in the previous eruption in 1994 — treating burn injuries caused by the hot clouds, and also treating broken bones," said Ning, the head of a local medical center.

Scientists raised the alert status for Merapi on Saturday to the highest level after weeks of volcanic activity, and by Sunday authorities had evacuated more than 4,500 people living in villages closest to the crater or next to rivers that could provide paths for hot lava.

They are now living in mosques, government buildings and schools.

Some 18,000 others who live lower down the slopes of the 9,800-foot mountain were not considered to be in immediate danger as of late Sunday. The mountain rises from the plains of Indonesia's densely populated Java island.

Police — who said there were no reports of damage or injuries — toured the danger zone on Monday, urging the last holdouts to leave.

But scores refused, saying they wanted to protect their land or livestock.

"I am calm because I have experienced this many times before," said Romadi, a 60-year-old villager whose house was covered in volcanic ash Monday. "Officials have told us to leave, but I know that it is not that dangerous."

Widi Sutikno, the official coordinating the government's emergency operation, commended those who recognized the danger and left Monday.

"I guess they didn't want to die after all," he said.

Merapi, which is one of 129 active volcanoes in Indonesia, sent out a searing cloud of gas that burned 60 people to death when it last erupted in 1994. About 1,300 people died in a 1930 eruption.

The deadly clouds of ash, gas and debris, known to volcanologists as pyroclastic flows, are the biggest worry for emergency services, said Sugiono, one of the scientists on a team monitoring the volcano 24 hours a day.

He said a glowing dome of lava being formed by magma forced to the surface was about to collapse and could cause a surge in the clouds.

Locals call the clouds "Wedhus Gembel," or "shaggy sheep clouds" because they resemble tightly curled balls of wool as they avalanche down the mountain at speeds of more than 60 miles an hour.

"If you get stuck in them, then you have no chance," Sugiono said.

"They are like a glowing avalanche that just incinerate everything in their path," said Lynton Jaques, from Australia's geoscience agency. "There is a real risk for people living on its flanks."

In one of the villages in the shadow of Merapi, holy men and hundreds of people lit incense and set rice, fruit and vegetables floating down a river in a ceremony they believed would appease the spirits and prevent an eruption.

"It's bound to help," Parsi, a villager, said after the ceremony. "Everyone around here believes in this. It is in our blood."

Although most Indonesians are Muslim, many also follow animist beliefs and worship ancient spirits, especially in the province of Central Java. Often at full moons, they trek to crater rims and throw in rice, jewelry and live animals to appease the volcano.

"All the things we are doing here are to try to make us safe," said Assize Ashore, an Islamic preacher who also took part in the ceremony. "Only Allah knows if Merapi will explode."

An 80-year-old man appointed by the nearby royal court as the volcano's spiritual guardian said he was not leaving, even though his house is within the mandatory evacuation zone. He said he believed the spirits that watch over the volcano would let him know if he was in danger.

"There is no risk," Maridjan said outside his home four miles from the crater. "I am still waiting here."

Maridjan was given the official title of "key holder of Mount Merapi" by the late king of the nearby court city, Jogjakarta. He leads yearly ceremonies when rice and flowers are thrown into the crater to appease spirits that he and most nearby villagers believe live over the mountain.

Maridjan's refusal to leave is angering local authorities in charge of evacuation efforts. They say he is setting a bad example and stopping other villagers from leaving.

"Only God knows what will happen. We can only ask for his protection," said Riskani, as her 8-year-old son played with toy trucks in a dusting of volcanic ash that fell on the village Monday.

"If it gets worse, we will leave. But for now, we are staying in this village," she said.

Some Javanese also believe increased activity at Merapi is a sign of impending political upheaval.

Merapi erupted in 1965 — a year before an aborted coup that ushered in Indonesia's long-ruling dictator Suharto — and activity also increased ahead of the 1997 Asian economic crisis.

Indonesia is prone to volcanic and seismic activity because it is part of the Pacific "Ring of Fire" — a series of fault lines stretching from the Western Hemisphere through Japan and Southeast Asia.