One of the world’s largest volcanos erupted without warning Monday morning.

Mount Aso, on the Japanese island of Kyushu, exploded without any warning tremors and is sending a plume of ash and smoke over a mile into the sky.

A group of 30 tourists who were near the crater at the time of the blast were safely recovered by police.

The Japanese Meteorological Agency raised the alert level for one of the mountain’s peaks to level 3 on a 5 level scale, meaning that the public should avoid the mountain out of fear of hot rocks shooting from the plume.

The volcano, located on the Pacific Ring of Fire, has produced more explosive eruptions than any other volcano in the world.  The caldera of the mountain is 12 miles in diameter and has smaller active peaks in the middle.

A 2.5 mile exclusion zone is now in effect around the mountain.  The area includes restaurants and museums but no residential homes.  All flights from nearby Kumanoto Airport have been cancelled or re-routed.