Four children have been seriously injured after a BMW being driven "erratically" collided with their family car on the outskirts of Oxford, police say.
Another two children sustained minor injuries. All six are being treated in hospital.
Officers said they tried to stop the BMW, which was being driven at high speed along the city's eastern bypass at 11.10pm on Tuesday.
The car carried on going, however, and five minutes later it collided with a VW Touran being driving along The Slade in the Headington area, east of Oxford city centre.
The driver of the Touran was left with minor injuries, while the children's ages have not been confirmed.
Five teenagers, all from Oxford, have been arrested on suspicion of causing serious injury by dangerous driving.
Three of them were also arrested on suspicion of failing to stop, driving a vehicle whilst unfit through drugs, and driving a vehicle dangerously.
One of the three, aged 18, is in custody while the other two, both 19, have been bailed.
Two further suspects, aged 18 and 19, have also been bailed.
Detective Inspector Justin Thomas, from Thames Valley Police's Serious Collision Investigation Unit, is appealing for information, plus dashcam or CCTV footage.
He said: "Our thoughts are with the family affected and specially trained officers will continue to support them throughout this investigation."
The force has referred itself to the Independent Office for Police Conduct watchdog, which it says is the "procedure in these circumstances".