Hot clouds were subsequently seen rolling down the mountain's slopes near Kutarakyat on the island of Sumatra, before drifting three miles south.
Airlines passing over the area have been issued with a "red notice" by the regional Volcanic Ash Advisory Centre in Darwin, Australia.
The stratovolcano first erupted in 2010, having previously lain dormant for four centuries, when an explosion killed two people. Sixteen were killed in a 2014 blast and seven more in 2016.
So far, no fatalities or injuries have been reported this time, according to the National Disaster Mitigation Agency spokesman Sutopo Purwo Nugroho.
Over 30,000 people have been forced to move away from homes near the mountain's base since the current series of eruptions began eight years ago.
The volcano is one of three currently erupting in Indonesia.
The country - situated on the Pacific's famous "Ring of Fire", known for its fault lines and seismic instability - has over 120 active volcanoes.