At least 27 people killed, including 12 pupils, as mud and debris hit North Sumatra province after heavy downpours.

Flash floods and landslides have killed at least 27 people, mostly children, on Indonesia‘s Sumatra island, officials say.

An Islamic school in Muara Saladi village saw the highest death toll after mud from the flood and debris from landslides struck Mandailing Natal district in North Sumatra province on Friday afternoon, local police chief Irsan Sinuhaji said on Saturday.

Rescuers and villagers on Friday managed to save several teachers and only 17 out of 29 school children who were swept away, said Sutopo Purwo Nugroho, the National Disaster Mitigation Agency’s spokesman.

He said rescuers retrieved the bodies of 11 children from mud and rubble hours after the incident and one more on Saturday.

A video obtained by The Associated Press showed relatives crying beside their loved ones at a health clinic where the bodies of the children were lying, covered with blankets.

Rescuers and villagers managed to save several teachers and 17 children [Antara Foto via Reuters]

Nugroho said two bodies were found early on Saturday from a car washed away by floods in Mandailing Natal, where 17 homes collapsed and 12 were swept away.

Hundreds of other homes were flooded up to two metres high, while landslides occurred in eight areas of the region.

Four villagers were killed after landslides hit 29 houses and flooded about 100 buildings in neighbouring Sibolga district, Nugroho said.

He said flash floods also smashed several villages in West Sumatra province’s Tanah Datar district, killing five people, including two children, and leaving another missing.

Landslides and flooding in the neighbouring districts of Padang Pariaman and West Pasaman killed four villagers after 500 houses flooded and three bridges collapsed.

Dozens of injured people were rushed to nearby hospitals and clinics [Khairul Bazar/AP]

Both North and West Sumatra provinces declared a weeklong emergency relief period.

Hundreds of survivors fled their hillside homes to safer ground, fearing more of the mountainside would collapse under continuing rain, Nugroho said.

Dozens of injured people were rushed to nearby hospitals and clinics, he said.

Seasonal downpours cause frequent landslides and floods each year in Indonesia, a chain of 17,000 islands where millions of people live in mountainous areas or near fertile flood plains.