Jakarta, Indonesia (CNN) -- A volcano erupted in Indonesia early Sunday, causing an estimated thousands of people to flee their homes, officials said.

There are no reports of casualties or injuries so far.

"The situation is under control. Emergency response teams are already on the scene," said Priyadi Kardono of the National Disaster Management Agency.

Mount Sinabung in North Sumatra had been inactive for more than 400 years. It had been classified as inactive by the Center for Volcanology and Geological Disaster Mitigation.

On Saturday, the center issued a warning and ordered evacuation of a 6 km (3.7 miles) radius around the volcano.

CNN's Andy Saputra contributed to this report.