Metro TV said thousands of people were moved by trucks and cars after Mount Merapi started spewing hot ash and volcanic rocks just before dusk, a day after authorities upgraded an alert status to the highest level.
Television footage showed residents, most wearing masks, being taken away in trucks with windscreens covered by dust.
‘This is an initial phase of an eruption,’ said Subandrio, head of the Volcanic Technology Development and Research Centre in Yogyakarta, who like many Indonesians uses only one name.
Metro TV reported that 15 badly burned bodies were found near the house of Mbah Marijan, the man known as the keeper of the mountain, who had refused to leave his home.
Yuniawan Wahyu Nugroho ( VIVANews.Com)
It said one of them was a journalist ( Yuniawan Wahyu Nugroho from VIVANews.COM) who climbed the mountain to interview Marijan.
An Indonesian Red Cross official said 13 people were injured and were being treated in a hospital.
Officials could not be reached immediately to confirm the report of deaths.
Vulcanologist Surono said three explosions were heard at around 6 p.m. (1100 GMT) and Merapi spewed clouds of black smoke 1,500-metre into the sky.
On Monday authorities began moving children and elderly people to some of the 60 emergency shelters after scientists upgraded the alert status as lava flowing down the cone’s slopes reached 4.5 km.
Tents, blankets and plastic sheeting were distributed to dozens of evacuation points around Yogyakarta and Central Java provinces, said Arief Setyo Hadi, an official with the Indonesian Red Cross.
Officials estimated up to 40,000 people were living in the endangered areas.
The 2,968-metre volcano last erupted in 2006, killing two people. Its most deadly eruption on record occurred in 1930 when 1,370 people were killed.
At least 66 people were killed in a 1994 eruption.