The death toll from floods and landslides on Indonesia's Sumatra island has risen to 21, with tens of thousands of people fleeing to temporary government shelters, officials said Sunday.

A river burst its banks and swept through mountainous villages in West Sumatra's Pesisir Selatan district late Friday, Doni Yusrizal, a spokesman for the National Disaster Management Agency, told reporters.

According to Yusrizal, seven bodies were found in Koto XI Tarusan village, while three others were found in two neighboring villages, bringing the total death toll to 21. However, seven people are still missing.

"Relief efforts for the dead and missing were hampered by power outages, blocked roads covered with thick mud and debris," Yusrizal said.

The agency said at least two villagers were injured, while more than 80,000 people have fled to temporary government shelters.

Flash floods and landslides are common in Indonesia, where millions of people live near flooded areas, especially during the rainy season. /AA