A volcano erupted overnight in northern Indonesia on Tuesday and forced hundreds of residents to evacuate, local authorities said, as they declared a maximum alert.

“Based on visual indications and instrument measurements, which show an increase in volcanic activity, the (alert) level at Mount Ruang has been raised from 3 to 4,” Hendra Gunawan, the director of Indonesia’s Volcanology Service, said in a statement. which was released late this afternoon.

Authorities also widened the evacuation zone from four to six kilometers around the crater.

The Ruang volcano, in the northeastern part of Kelevis, reaches a height of 725 meters. The first explosion occurred at 21:45 local time on Tuesday, followed by two more in the early hours of Wednesday morning.

No casualties were reported, but 800 people were evacuated from two villages on Ruang Island and taken to a neighboring island, Indonesia’s Antara news agency reported.

The volcanology service said residents of Tagulandang should move outside the six-kilometer radius of the crater by Wednesday night. Hendra Gunawan also warned residents to be alert because rocks could be thrown from the crater or a tsunami could be caused by the collapse of the volcano into the sea.

From the first explosion the ash cloud reached a height of 2 kilometers and from the second to 2.5, said Muhammad Wafid, the director of the national geological survey.

The activity of the Ruang volcano intensified after two earthquakes occurred in the last few days.

Indonesia sits on the Pacific Rim of Fire, where continental plates collide causing significant volcanic and seismic activity. The country has almost 130 active volcanoes.