Two people have been taken to hospital after a serious collision near Rushden late on Friday night (November 21).
The A45 between Wellingborough and Rushden was closed for four hours after a black Renault Clio collided with a signpost, hit a tree and caught fire.
Police say the 28-year-old driver was thrown from the vehicle, with the passenger being trapped inside after the car came to rest in a ditch.
Both men were taken to Northampton General Hospital. The driver of the vehicle was later transferred to University Hospital, Coventry, and is said to be in a critical condition.
The incident took place on the eastbound carriageway near junction 16 for Rushden just after 11pm, with the road not being reopened until 3am.
Police extinguished the car fire, while the fire service helped cut one person free from the vehicle.
Officers want to speak to anyone who witnessed the collision, or saw the vehicle just before it happened.
Anyone with information or who witnessed this incident is asked to call the Drivewatch Hotline on 0800 174675.