Indonesia’s Mount Ruang volcano erupted at least five times on Wednesday, prompting a high-level alert for more eruptions and a tsunami warning.

Over 11,000 people living near the volcano were ordered to leave as the government struggled to create a four-mile-radius safe zone around the mountain.

Ruang itself is an islet about three miles across at its widest point, separated from the much larger and more heavily populated Tagulandang Island by a narrow strait. The volcano has erupted several times over the past two centuries, most recently in 2002.

Beginning on Tuesday night, the volcano was rocked by a series of increasingly powerful explosions, causing lava to pour out of its crater as the mountain was wreathed in clouds and lighting bolts. As of Wednesday morning, over 400 volcanic earthquakes had been detected around the island.

Indonesian rescue workers scrambled to evacuate the area, aided by local fishermen who offered their boats for transportation. The Indonesian Navy dispatched a warship that was able to evacuate 195 people.

Eruptions continued on Thursday and Friday, pelting houses on Tagulandang with volcanic rock and making some roads difficult to use. 

Most of Tagulandang’s 2,000 residents were told to leave their homes, an advisory issued after some of them had already begun to flee in panic. 

Tagulandang also has a small prison, whose handful of inmates and staff were evacuated to nearby Sulawesi island. Much of Tagulandang’s population could ultimately be evacuated to Sulawesi, which is about six hours away by boat.

Several airlines servicing the region announced canceled flights, and the Sam Ratulangi International Airport, located about 60 miles from the volcano, was closed on Wednesday and Thursday due to clouds of volcanic ash.

Australia’s Bureau of Meteorology estimated that Mount Ruang blew volcanic ash some 70,000 feet into the atmosphere.

Another fear is that part of Mount Ruang will be dislodged by the eruptions and fall into the sea. Indonesia’s volcano agency warned residents of the region to brace themselves for a possible tsunami on Wednesday, haunted by memories of Mount Anak Krakatoa unleashing a tsunami that killed over 400 people when it erupted in 2018.

Indonesian officials said on Friday morning that the volcano appeared to be calming, but a few hours after that statement the mountain began belching ash again, to the surprise and horror of area residents.