Clouds of deadly hot ash, rock fragments and volcanic gas surged down Mount Merapi's slopes Monday, as activity at the towering volcano intensified to its highest level yet. One of the eruptions sent an avalanche of debris and ash rolling almost four kilometers (2.5 miles) down the mountain's western flank, said Ratdomopurbo, the region's chief volcanologist. A string of other explosions throughout the day triggered other massive clouds. Many people who earlier refused to leave the danger zone fled in buses or trucks. Villages near the 3,000-meter (9,800-foot) peak resembled ghost towns, with only a few young men to be seen. Most houses, some dusted with ash, were deserted and shops closed. "I am panicking this time," said Katimi, a mother of three and one of thousands of people seeking shelter in mosques, government buildings and schools designated as evacuation points. "Merapi appears angry." Scientists raised the alert status for Merapi to the highest level Saturday after weeks of volcanic activity, evacuating more than 4,500 people living near the crater or next to rivers that could provide paths for hot lava. Some 200 villagers living within the danger zone refused to budge, saying they did not want to abandon their land or livestock, but Monday's volatile activity convinced others it was time to go. They jumped into vans with their belongings and headed down the mountain. "I guess they didn't want to die after all," said Widi Sutikno, the official coordinating the government's emergency operation. Others remained adamant, saying they were prepared to hold out a little longer. "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." Some 18,000 people on the lower slopes of the mountain, which rises from the plains of Indonesia's densely populated Java Island, were not considered to be in immediate danger. The deadly clouds of ash, gas and debris, known to volcanologists as pyroclastic flows, are the biggest threat to people on the slopes, who choose to live there because its fertile volcanic soil makes for bumper crops. A growing dome of lava being formed by magma forced to the surface was poised to collapse and could a trigger a surge in the clouds, as happened in the 1994 disaster, officials have said. Many mystic beliefs are associated with the mountain, and some Javanese also believe increased activity at Merapi is a sign of impending political upheaval. Although most Indonesians are Muslim, many also follow animist beliefs and worship ancient spirits, especially in central Java province. 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."