A boat carrying Nigerian students capsized in Kano state in northern Nigeria, killing at least 29, local officials said on Wednesday.

The boat on the Watari dam was carrying roughly 40 students from an Islamic school, most of whom were under 18, and capsized around 5:30 local time Tuesday evening, a local government official said.

Kano state fire service spokesperson Saminu Yusuf Abdullahi said rescuers had recovered 29 dead bodies.

“What we know is that the boat was overloaded,” Abdullahi said.

Local government official Aminu Bello Gogori said seven students had been rescued and were receiving hospital treatment.

Two locals, Umar Shuaibu and Tanko Isa, said that while there were some adults on the boat, most were under 18, with some as young as 6 years old. They said all seven rescued were children.