"It happened so fast," said Surono, the director of the volcanology and mitigation agency. "There was no time for an evacuation."
Indonesia volcano spews lava, gas; 4 feared dead →
The government sent dozens of trucks to the mountain to help carry them back before Tuesday's eruption, which sent ash and debris shooting three miles into the air, said Surono, who heads the nation's volcano alert center.
Indonesian volcano erupts again →