The mountain’s biggest eruption in more than a century has rained burning ash outside the official danger zone and has forced thousands to flee. According to rescue workers, there was panic and chaos on the roads as residents tried to flee in the darkness.
Mount Merapi is located in a densely-populated area in central Java, where 100,000 people have been evacuated from danger zones.
Many of the dead were children from the village of Argomulyo, 18 kms from the crater.
A river running through the village also overflowed with a thick mixture of mud and ash, and several bodies lay unclaimed in the debris, witnesses say.
"I found three bodies: a child, mother and father, still on their bed. They must have been sleeping when the hot ash struck their house," rescuer Utha told AFP in Argomulyo.