Some 150 members of an Islamic scouts group, aged from 13 to 15 years old, were walking along the Cileuleur River when 21 are thought to have attempted to ford the water.

Nearby locals managed to pull 10 to safety, said Supriono – who, like many Indonesians, only has one name – an official with Bandung’s search and rescue team.

“Two students … are in a critical condition in the hospital, while 11 were found dead,” he told AFP.

Authorities are still investigating the cause of the accident, as well as working to ensure all on the trip have been accounted for.

The students were trekking and cleaning the riverbank, despite official warnings from the national disaster mitigation agency.

River trekking is banned for children and teenagers during the rainy season, which starts in late November.

In February last year, 10 scouts died after they were swept away by a flash flood that also left nearly two dozen injured.