Officials said Mount Sinabung in North Sumatra province started rumbling a few days ago. It sent sand and ash flying into the air over a kilometre high but lava only moved near the crater. The morning eruption had mostly stopped on Sunday.
The eruption caused no major damage and only really covered plants and trees with dust. Officials say Mount Sinabung last erupted in 1600, so observers don't know the volcano's eruption pattern and are closely monitoring it for more activity.
Up to 10,000 people fled when the volcano started rumbling, and they've been staying in government buildings, houses of worship and other evacuation centres in nearby towns.
The government distributed thousands of masks to refugees and set up public kitchens so people can cook food.
Indonesia is no stranger to volcanic eruptions. The world's largest archipelago sits on the 'Ring of Fire,' an arc of volcanoes and fault lines around the Pacific Basin.
With files from The Associated Press