A volcano in eastern Indonesia erupted overnight killing at least six people as it spewed fireballs and ash on surrounding villages, officials said Monday, as they raised its alert status to the highest level, Paralel.Az reports citing NDTV.

Mount Lewotobi Laki-Laki, a 1,703-metre (5,587-feet) twin volcano located on the popular tourist island of Flores, first erupted shortly before midnight, forcing authorities to evacuate several villages.

"Six fatalities have been confirmed," Abdul Muhari, spokesman of the country's disaster mitigation agency (BNPB), told Kompas TV.

Footage received by AFP showed villages near the volcano covered by thick ash, with some areas on fire.

An AFP journalist near the volcano said five villages evacuated, affecting thousands of residents.

Some wooden houses caught fire, and the ground was pockmarked with holes caused by flying molten rocks.

The crater erupted just before midnight and then again at 1:27 am (1727 GMT Sunday) and 2:48 am, the country's volcanology agency said.

It raised the alert level to the highest and told locals and tourists not to carry out activities within a seven-kilometre (4.3-mile) radius of the crater.

"There has been a significant increase in volcanic activity on Mount Lewotobi Laki-laki," it said in a press release Monday.

It released images that showed the roofs of houses collapsed after they were hit by volcanic rocks, and locals sheltering in communal buildings.