The victims were farming in an area that was declared unsafe because of its close proximity to Mount Sinabung.
The volcano was still spewing ash on Sunday, hampering rescue operations.
More than a dozen people were killed when it erupted in 2014. It also erupted in 2010, after having been dormant for 400 years.
Rescue teams are still scouring the area, looking for more victims who may have been killed or badly burned by the hot gas and ash clouds released in the eruption.
Rescue teams were searching homes and farms in the village of Gamber, which was also evacuated in 2014.
What causes volcanoes?
The 2,460-metre (8,070 foot) tall volcano is among the country's most active.
Indonesia, located on the Pacific Ring of Fire, has more than 120 active volcanoes.
Seven people have been killed after a volcano in western Indonesia erupted, blasting clouds of volcanic ash 3km (2 miles) into the sky.