"Right now residents are being evacuated. About half of them are still on rooftops waiting for help."

The dam was holding about two million cubic metres of water on the Pesanggrahan river.

More deaths feared

Rescue officials say they fear the death toll could rise much further because the dam collapsed when many people were asleep.

"It was like being in the middle of a tsunami"

Minu, local resident

"It was like being in the middle of a tsunami," Minu, a local resident told Detikcom, a news website.

"People were screaming 'the water's coming in, the water's coming in,' and our dog was barking. I could hear our door being pounded on and I wondered who could it be, but it was the water."

Floods and landslides are common in Indonesia during the wet season, which falls around the northern hemisphere's summer.