More than 20,000 people living near Mount Sinabung on the Indonesian island of Sumatra have been evacuated after the volcano erupted on Sunday for the first time in 400 years, local media said. Earlier reports said at least 12,000 people from villages within a 6 kilometer (3.7 miles) radius of the volcano were evacuated to government-provided shelters outside the danger zone. A vast cloud of ash and smoke is hanging over the area, causing some local flights to be suspended. Mount Sinabung erupted again on Monday, Indonesian officials said.