Efforts were underway on Monday to rescue several hundred trekkers stranded on Mount Rinjani on Indonesia’s Lombok Island, a day after a powerful 6.4 magnitude earthquake struck the popular tourist destination, a disaster agency official said, Reuters reported.

Sutopo Purwo Nugroho, the disaster mitigation agency spokesman, said on Twitter late on Sunday that out of 820 people on the slopes of the volcano when the quake struck, 246 had been successfully evacuated.

He said 617 of those trekking at the time were foreigners.

Agung Pramuja, an official of the West Nusa Tenggara Disaster Mitigation Agency, said the death toll from Sunday’s earthquake stood at 16.

“The latest information from the team in the field is that today all the families stuck on Mount Rinjani will be evacuated via the Sembalun trail,” said Asdiyanto, an official at the North Lombok Disaster Mitigation Agency.

“This is being handled by the management team from Mount Rinjani National Park,” said Asdiyanto who, like many Indonesians, uses one name.

A magnitude 6.4 earthquake is considered strong and is capable of causing severe damage.

The Lombok quake struck at 6:47 a.m. (2247 GMT on Saturday) and was only 4.35 miles deep (7 km), a shallow depth that would have amplified its effect.

It was centered 50 km (31 miles) northeast of the city of Mataram, according to the U.S. Geological Survey, but it was also felt strongly to the west on the neighboring island of Bali, Indonesia’s top tourist destination.

Earthquakes are common in Indonesia, which is located on the seismically active “Ring of Fire” on the rim of the Pacific Ocean.