Indonesia’s Mount Merapi started to erupt on Tuesday, spewing hot ash and rocks into the air.
The government raised the state of alert to its highest level.
The military has deployed trucks and buses to help bring people to safety.
Officials said they would evacuate more than 11,000 people from the affected area, which is situated 460 kilometres from the capital of Jakarta.
Indonesia Vice President Boediono visited those forced to leave their homes.
Mount Merapi, which is the country’s most volatile volcano last erupted four years ago, killing two people.
A 1994 eruption claimed 70 lives, while 1,300 were killed in 1930.
Indonesia sits on the Asia Pacific’s so-called Ring of Fire: a region that has 130 active volcanoes.