Villagers have been warned to stay several kilometres away from Indonesia's most active volcano after it erupted, spewing sand and pyroclastic material and sending massive smoke-and-ash column as high as 6000 metres into the sky.
Indonesia's Geology and Volcanology Research Agency said the eruption of Mount Merapi on the main island of Java on Tuesday morning at 5am local time also unleashed searing gas clouds two kilometres down its slopes.
The volcano has rumbled and generated dark hot clouds since last year.
Its last major eruption in 2010 killed 353 people.
The huge plume of volcano ash from the so-called "Mountain of Fire" threatened several villages as it made the rain thick and muddy and the terrain near impossible to pass.
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Speculator vision has been posted on social media show ash from the volcano, which in October 2010 killed 36 people and destroyed several villages.
Witnesses said the sound was heard 30 kilometres away.
The agency did not raise the alert status of Merapi, which already was at the third-highest level due to its ongoing activity.
The 2968-metre mountain is the most active of 500 Indonesian volcanoes.
Indonesia, an archipelago of 240 million people, is prone to earthquakes and volcanic activity because it sits along the Pacific "Ring of Fire," a horseshoe-shaped series of fault lines around the ocean.