Mount Aso in Kumamoto Prefecture, southwestern Japan, has erupted.
The Meteorological Agency says the volcano erupted at 6:28 p.m. on Tuesday. Smoke mixed with volcanic ash rose about 200 meters from the mountain's crater.
The agency raised the alert level for Mount Aso to two on a scale of one to five on Sunday, after detecting active volcanic tremors and an increase in volcanic gas emissions.
People within roughly one kilometer of the crater are being urged to stay alert for huge airborne volcanic rocks and pyroclastic flows.
Mount Aso last erupted in October 2016.