(CNN) — Mount Ontake erupted late Saturday morning, sending a plume of smoke and ash into the sky, the Japan Meteorological Agency reported.
At least three people have been injured, said a task force in Otaki village, just south of the volcano. They have observed 17-20 inches of volcanic ash covering the ground.
Local authorities said there were roughly 150 hikers in the area at the time, according to the agency, which raised the Volcanic Alert Level for Ontake from 1 to 3.
The public is advised to not approach the volcano, and police and firefighters have deployed to help hikers near the summit.
About 250 people living near the mountain have decided to remain in their homes, police said.
The volcano last erupted in 2007.
It is located about 155 miles west of Tokyo.