The accident occurred on the Bogra-Rangpur highway at Gaibandha.
Four were killed on the spot and the rest succumbed to their injuries at a nearby hospital, police station chief Faruk Ahmed was quoted as saying by the Daily Star.
The accident took place when a local bus collided head-on with a Rangpur-bound Hanif Paribahan bus at Boali area on the highway around 4.30 pm, he said.
One bus skidded off the highway into a ditch, Ahmed said.
Several children were among the dead.