the Ring Of Fire's Hot Spot: Mount MERAPI volcano, central Java, Indonesia, is smokin', tremblin' & boomin', expected to erupt, but only Merapi knows when and how big / BBC video
Indonesia's most volatile volcano is erupting, spewing plumes of hot ash and hurling rocks into the air.
Officials say Mount Merapi, in central Java, began erupting just before dusk on Tuesday.
Scientists warn the pressure building up beneath its lava dome could lead to one of the most powerful blasts in years.
Thousands of residents living on the volcano's slopes have been evacuated.
However, a further 13,000 people need to be evacuated from within a 10-mile (16km) radius of the volcano, officials say.
Television footage showed thousands of people fleeing the area, some covered in the volcano's white ash which rained from the sky.
[image] People evacuated by boat from Mount Merapi Many thousands of people have yet to be evacuated
It is thought that 5,000 people live on or near the volcano.
The head of one village near the volcano said that many residents were stranded. He said rain loaded with volcanic ash had reduced visibility to just 5m (16ft).
"We are evacuating to the village square, around 14km from Mount Merapi slope. Some of the villagers are still stranded but we received text messages from them, saying that they are OK," Heri Suprapto told the BBC.
A doctor at a nearby hospital said at least six people had been badly burnt by the hot air rushing from the volcano, Reuters reports. One eyewitness said he saw people with bad burns being taken away on stretchers, the agency reports.
There were also reports that a three-month-old baby had died from breathing difficulties after inhaling volcanic material.
On Monday, officials monitoring the volcano raised the alert for Mount Merapi to the highest possible level.
Since then, more than 600 volcanic earthquakes have been recorded around the mountain.
"We heard three explosions around 1800 (1100 GMT) spewing volcanic material as high as 1.5km (one mile) and sending heat clouds down the slopes," government volcanologist Surono, who goes by one name, told AFP.
He warned that pressure was building up behind a lava dome near the crater.
"We hope it will release slowly," he said. "Otherwise, we're looking at a potentially huge eruption, bigger than anything we've seen in years."
He said this eruption was more powerful than the volcano's last blast, in 2006, which killed two people.
In 1930 another powerful eruption wiped out 13 villages, killing more than 1,000 people.
Thousands of people living near the volcano have been ordered to move to safer ground, but many are still refusing to leave.
Some are refusing to heed the warnings because they do not want to leave their livestock and properties behind.
Ponco Sumarto, 65, who arrived at a makeshift camp with her two grandchildren, said her children had stayed behind to look after their crops.
A woman flees the volcano in Kaliurang village, Indonesia
"I just have to follow orders to take shelter here for safety, even though I'd rather like to stay at home," the Associated Press news agency quoted her as saying.
BBC Indonesia correspondent Karishma Vaswani says that for many Javanese, Mt Merapi is a sacred site.
Officials say some of the villagers are waiting for the local "gatekeeper" of the volcano to tell them that the increased activity at Mt Merapi is dangerous.
Described as a medicine man, he is believed by many villagers to have a spiritual connection to the volcano.
He has reportedly said he will not leave yet, but is urging villagers to make their way to government shelters, our correspondent says.
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