Mount Merapi volcano has erupted for a third time, with local people reportedly saying this was louder and stronger than the previous eruption on Tuesday.
The latest eruption happened at around 0100 on Saturday (1800GMT Friday).Agence France Presse reported that it caused panic, with hundreds of people, including police and soldiers, trying to flee in cars or on motorbikes.
Ash was raining down in Yogyakarta, about 30km (19 miles) away.
Burgess, a photography student from Australia, is in Yogyakarta. He told the BBC: "I was in a nightclub when a friend called to say there was a load of ash. I went outside and saw ash falling like snow."
But authorities say Yogyakarta is safe. The head of the monitoring body has said the risk remains lmited to the 10km zone around the mountain.
Nearer that zone, though, people felt more in danger.
"I heard several sounds like thunder," Mukimen, a mother-of-two who was fleeing with her family, told AFP. "I was so scared I was shaking."
There had been a number of small eruptions earlier on Friday but with no casualties reported.
Earlier, officials said two people who suffered burns from Tuesday's eruption had died from their injuries, bringing the confirmed death toll to 35.
Displaced people
At least 47,000 people who live around Mount Merapi are staying in government camps or with friends and relatives, according to the National Disaster Management Agency.
But there are frequent reports of displaced people returning to check on their properties or livestock.
Government volcanologist Subandrio told AFP the new eruption suggested the government should be "more serious" about enforcing the exclusion zone and possibly widening it.
Alert levels have been raised on four other volcanoes, two of which are definitely showing signs of activity - Anak Krakatau and Mount Semeru.
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