Indonesian authorities on Wednesday ordered hundreds of villagers to evacuate following multiple eruptions of a remote island volcano, raising fears it could collapse into the sea and trigger a tsunami.

Mount Ruang, a 725-meter (2,400-foot) volcano on Ruang Island, North Sulawesi, has erupted at least five times since Tuesday night, spewing fiery lava and ash plumes thousands of feet into the sky, the country’s volcanology agency said.

Agency chief Hendra Gunawan said officials had raised the volcano alert to the highest level, warning people not to go within 6 kilometers (3.7 miles) of the peak, due to fears Mount Ruang could partially collapse into the water and cause a tsunami, as it did in 1871.

“The force of Mount Ruang’s eruption is getting bigger and has emitted hot clouds of approximately 1.7 kilometers,” he told national news agency Antara, adding the eruptions were triggered by recent earthquakes in the area.

Mount Ruang is a stratovolcano, which are typically conical and relatively steep-sided due to the formation of viscous, sticky lava that does not flow easily. Stratovolcanoes often produces explosive eruptions due to gas build-up in the magma, according to volcanologists.

Dramatic footage of the eruptions Wednesday shows plumes of gray ash billowing into the sky and streams of glowing lava, accompanied by lightning strikes. Images also show villagers being evacuated.

Ruang Island is home to about 800 residents, who have temporarily relocated to neighboring Tagulandang Island, according to authorities. People on Tagulandang should watch for falling incandescent rocks and hot cloud surges, officials warned.

No casualties have been reported.

Indonesia, a Southeast Asian archipelago of 270 million people, has over 120 active volcanoes – more than anywhere else in the world. It sits along the Ring of Fire, a 25,000-mile (40,000-kilometer) arc of seismic fault lines around the Pacific Ocean.

In 2018, the eruption of Indonesia’s Anak Krakatau caused it to topple into the sea, triggering a tsunami that struck the coasts of the main Java and Sumatra islands, killing more than 400 people.

This story has been updated with additional information.