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.

These secondary populations could also be utilised in a way to reduce or halt the pressure on species' native populations, say researchers.
Adopting a more creative approach to conservation could help slow global biodiversity loss, they added.
The findings appear in the Frontiers in Ecology and the Environment journal.
"This first came to my attention when I read a news story about the seizure of an illegal shipment of 23 yellow crested cockatoos," said co-author Luke Gibson from the University of Hong Kong.
"Each individual had been stuffed inside a plastic water bottle."
He learned that the species was critically endangered, which surprised him. "I had been seeing the same species flying around directly outside my office at the university," he added.
This prompted Dr Gibson and his colleague Din Li Yong to investigate how a critically endangered species had become established as a self-sustaining outside of its natural range.
They discovered 49 cases of a globally threatened species becoming established as a separate population, including the the yellow crested cockatoo on Hong Kong island.
"This is a species which is primarily threatened by wildlife trade," he told BBC News.
"Poachers go out into the forest in its native range in eastern Indonesia and capture the bird and then ship them off, usually up to Hong Kong or China where there is a strong demand for pet birds.
"This is what has fuelled the decline of this species [in its native range]. But it's really interesting because that same cause also had another effect: some of the people who were keeping this species in Hong Kong accidentally or intentionally released them."
As a result of enough of the birds being released, it allowed a new self-sustaining population to be be established on the island.
The government in Hong Kong has made it illegal to capture the species, even though it is a non-native species.
Because the city-state is affluent and relatively well educated, the cases of people breaking the law are extremely rare, explained Dr Gibson. Unlike in its native range in Indonesia where capturing birds forms a major source of income.
However, there can be downsides to the newly established population of endangered species, such as a limited genetic pool, contracting novel diseases, or hybridisation with closely related species, Dr Gibson added.
However, it did also present a possible "very interesting" opportunity for conservationists, he suggested.
This would involve "harvesting" some of the newly established secondary population. This would allow demands in the wildlife trade to be met but also relieve the pressures on the native populations.
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He said he had been inspired by Pope Francis's call for peace and dialogue.
Demonstrators set fire to the Congress building last month in protest at a secret Senate vote to allow second terms.
Paraguay suffered under decades of dictatorship until 1989 and many oppose presidential re-election.
Senators say they will continue to campaign for a vote in the lower house.
They  argue that Paraguay is the only country in Latin America that does not allow second terms and it needs to modernise its constitution.
During the riots, police shot dead a demonstrator which triggered calls for crisis talks backed by Pope Francis.
They fell apart when the main opposition, the Liberal Party, boycotted them.
The conservative president had the backing of his leftist rival Fernando Lugo, who was president from 2008 to 2012 and also wants to run again.
Seven people have been killed after a volcano in western Indonesia erupted, blasting clouds of volcanic ash 3km (2 miles) into the sky.
[NEXT_CONCEPT]
Illegally traded endangered species that escape, forming secondary populations, offer hope for their long-term survival, a study suggests.
[NEXT_CONCEPT]
The President of Paraguay, Horacio Cartes, says he will no longer seek re-election after his bid to change the constitution triggered rioting.