Two have been taken to hospital so far, but three more need some form of care, said Johan Håkansson, press spokesman for the police in Region West at 1 p.m.
Everyone was conscious and able to speak when rescue workers arrived at the scene.
The accident has been described by witnesses as a pile-up where a vehicle braked sharply after a collision. A truck, two minibuses and a passenger car are said to be involved. The schoolchildren are said to have been travelling in one of the minibuses.
The road was completely closed to traffic at the accident scene at lunchtime.
