Indonesian officials on Monday said the death toll from flash floods and mudslides in Western Sumatra had risen to at least 41 people.

Rescue teams were still searching for another 17 people who remain missing, authorities added.

Torrential rain on Saturday evening caused flash floods, landslides, and cold lava flow, which is a mixture of volcanic ash, rock debris and water that flows like mud, in three districts in West Sumatra province, according to officials.

The cold lava flow, known in Indonesia as a lahar, came from Mount Marapi, one of Sumatra's most active volcanoes.

Officials said around 400 personnel, consisting of local rescuers, police, and military were deployed to search for the missing people on Monday, helped by excavators and drones.

The rescue efforts that began on Sunday were complicated by damaged roads, making it difficult for rescuers to pass through.

The national disaster and management agency (BNPB) said almost 200 houses were damaged and 72 hectares of land, including rice fields, were affected.

At least 159 people had been evacuated to nearby school buildings, the BNPB said. (Reuters)