The mayor of the town of Fundacion near the Caribbean coast told Caracol Radio the burned bodies of 26 children had been found and President Juan Manuel Santos lamented on Twitter an accident causing at least 15 deaths.
The mayor, Luz Stella Duran, said 40 to 50 children had been traveling on the bus accompanied only by the driver. Around 10 children were receiving medical attention, she said.
Pictures on local media web sites showed the charred, smoking frame of the burned bus. It was not clear how the fire started.