A powerful burst of hot ash and gravel has erupted from a rumbling volcano in western Indonesia, sending panicking villages fleeing down the mountain.

Authorities raised the alert status to the highest level on Sunday after Mount Sinabung had a series of eruptions. Six more eruptions early Monday sent volcanic debris as high as 2,000 meters (6,500 feet) into the air.

National Disaster Mitigation Agency spokesman Sutopo Purwo Nugroho says about 15,000 people have been evacuated from 17 villages in the danger zone, a 5-kilometer (3-mile) area around the crater.

Transportation Ministry spokesman Bambang Ervan said airlines had been notified to avoid routes near the mountain in North Sumatra province.