A teenager was seriously injured after a car she was travelling in left the road and hit a tree.
The crash happened at around 6.10pm in Rushton Road, between Desborough and Rushton on Thursday.
A silver Vauxhall Vectra, driven by a 41-year-old man from Kettering, was travelling towards Rushton when it left the road, hit a tree and rolled over.
It is not known at the moment why the car left the road, according to police.
One of the passengers, a 15-year-old girl, was taken by the Derbyshire, Leicestershire & Rutland Air Ambulance (DLRAA) to University Hospital Coventry with serious injuries.
The driver and the second passenger, a 13-year-old girl, were also taken to hospital with minor injuries.
A spokesman for the air ambulance said: “DLRAA landed at the scene at around 6.38pm. On their arrival, the patient was being extricated from the vehicle by the local fire and rescue service.
“Once freed, the patient was stabilised and treated at the scene before being airlifted to University Hospitals Coventry & Warwickshire for further treatment. Her current condition is unknown. The driver was treated at the scene by the EMAS crew.”
Witnesses to this incident, or anyone who has any information, can call Northamptonshire Police on 101 or call the Drivewatch Hotline on 0800 174615.