Seven people were killed and two were in critical condition after Mount Sinabung's volcano erupted on Sumatra island as the army and police searched for survivors.
The volcano continued to spew hot ash on Sunday, making it dangerous for rescuers, National Disaster Mitigation Agency spokesman Sutopo Purwo Nugroho said.
Mount Sinabung is among the country's most active volcanoes. More than a dozen people were killed and thousands evacuated when Sinabung erupted in 2014.
The seven dead and two injured were found in the village of Gamber.
"It is not immediately clear how many people were in Gamber because when the mountain spewed clouds of hot ash, there was not supposed to be any activity in the area," Sutopo said.
Indonesia, located on the Pacific Rim of Fire, has more than 120 active volcanoes.