At least 13 students were killed on Monday after a school bus collided with a truck in Gauteng province, South Africa, authorities reported.

Police said 11 children died at the scene, while two others later succumbed to their injuries in the hospital.

The small private bus was transporting pupils to and from primary and secondary schools southwest of Johannesburg when the collision occurred around 7 a.m.

Witnesses said the bus had attempted to overtake a row of parked vehicles before colliding head-on with the truck.

Authorities have launched an investigation into the circumstances of the accident.