Mount Lewotobi Laki-laki, on Flores Island in East Nusa Tenggara province, erupted at midnight on Sunday (3am Monday AEDT), belching a fiery-red column of lava, volcanic ash and incandescent rocks, Hadi Wijaya, a spokesperson for The Center of Volcanology and Geological Hazard Mitigation (PVMBG), said.
"After the eruption, there was power outage and then it was raining and big lightning which caused panic among residents," he told Reuters, adding that the authority had raised the status of the volcano to level IV or the highest.
The agency has recommended a seven-kilometre radius be cleared.
Authorities have started evacuating residents to other villages located around 20km from the crater. (AP PHOTO)
Fiery lava and rocks hit the nearest settlements around four kilometres from the crater, burning and damaging residents' houses, Hadi said.
As of Monday morning at least nine people had died, said Heronimus Lamawuran, a local official at East Flores area, adding the eruption had affected seven villages.
"We have started evacuating residents since this morning to other villages located around 20km from the crater," he said.
The nearest villages were covered by thick volcanic ash, he said.
The authorities are still gathering data on the number of evacuees and damaged buildings.
Indonesia sits on the "Pacific Ring of Fire", an area of high seismic activity atop multiple tectonic plates.
This eruption follows a series of eruptions of different volcanoes in Indonesia.
In May, a volcano on the remote island of Halmahera, Mount Ibu, caused evacuation of people from seven villages.
North Sulawesi's Ruang volcano has also erupted in May and prompted authorities to evacuate more than 12,000 people.
Flash floods and cold lava flow from Mount Marapi in West Sumatra province, covered several nearby districts following torrential rain on May 11, killing more than 60 people.
