On Friday, the Indonesian Center for Vulcanology of Geological Hazard Mitigation raised Mountain Agung's alert status to Level 4 -- the highest -- after a "tremendous increase" in seismic activity.

"Volcanic activity remains high and there are indications of magma rising to the surface and causing tremors," Sutopo Purwo Nugroho of the National Disaster Management Agency said.

People were ordered to evacuate from a radius of 6 to 8 miles around the mountain. Others left voluntarily.

Gov. Mangku Pastika said another 50,000 people could end up in shelters if the volcano erupts.

They are staying in temporary shelters, sport centers, village halls and with relatives or friends.

Truck driver Wayan Suparta, 35, decided to flee with his family from their home that is 3 miles from the mountain.