Officials were searching Sunday for the bodies of two children as small explosions could be heard from a volcano that erupted a day earlier, killing six people on a small island in eastern Indonesia.

Ash and smoke shot about a mile into the air after Mount Rokatenda in East Nusa Tenggara province erupted early Saturday morning. Nearly 3,000 people have been evacuated from the area on Palue island, according to the National Disaster Mitigation Agency. The volcano has been rumbling since last October.

The victims who died included three adults and two children, said agency spokesman Sutopo Purwo Nugroho, adding the age of the sixth person killed was not known. He said that the adults’ bodies were recovered, but that the children’s remains had not been found.

Tini Thadeus, head of the local disaster agency, said Sunday he was pessimistic about recovering the bodies since they were buried under heat volcanic material.

He said small explosions could be heard coming from the peak, which was still sending smoke up to 600 meters (yards) into the sky.

“But all of the villagers have been evacuated out of the danger zone” near the crater, Thadeus said from the provincial capital, Kupang.

The eruption lasted about seven minutes, said Frans Wangge, who heads the volcano’s monitoring post. He said hot lava burned trees around the beach and villages, and made it difficult to reach the area where the victims were killed.

Mount Rokatenda is one of 129 active volcanoes in Indonesia, an archipelago of more than 17,000 islands that’s home to 240 million people. The country is prone to earthquakes and volcanic activity because it sits along the Pacific “Ring of Fire,” a horseshoe-shaped series of fault lines.