Police on Saturday questioned three workers suspected of accidentally starting a fire that killed 20 people in a third-floor karaoke bar in one of Indonesia's largest cities, an official said.
Two survivors of the Friday night fire in Medan on Sumatra island remained in critical condition Saturday.
Police questioned three laborers about the fire, Medan chief detective Col. Agus Andrianto said.
The workers had been told to cut a synthetic rug in a back room of the bar, Andrianto said.
Police suspect that they attempted to melt through the rug with a cigarette lighter and accidentally set it on fire, he said.
They could be sentenced to up to five years in prison if convicted of committing a negligent act that caused death or injury, Andrianto said.
The bodies of 11 men and nine women were recovered from the charred debris of the bar Friday night and firefighters found no more victims Saturday, he said.
Some witnesses told local television that the blaze may have been caused by an electrical short circuit.