The Mount Gamalama volcano in North Maluku province erupted late Thursday, sending ash and rocks 2 000m into the sky, said Sutopo Nugroho, a spokesperson for the National Disaster Management Agency.
The victims, all mountain climbers, were injured while running to escape the eruption, and not by volcanic materials, Sutopo said.
One person from the group was still unaccounted for, he said.
The volcanic ash was still blanketing much of the city of Ternate on Friday morning, Sutopo said.