A man was taken to hospital with head, chest and spinal injuries after the car he was driving crashed into a road sign.
Firefighters had to rescue the driver, who was trapped in the BMW following the accident on the A59 at Brockholes, Preston, at around 1.50pm on Saturday.
The road was temporarily closed while officers used cutters and spreaders to remove the roof of the car.
They said the car was the only vehicle involved in the incident.
Crew manager Paul Rigden said: “The car had hit a road sign. We cut the roof off the car and the man was treated at the scene for head, chest and also spine injuries, so he came out on a spine board.”
The man, thought to be in his 30s, was then taken to Royal Preston Hospital by ambulance.
His injuries are not thought to have been serious.