A teenager was badly hurt after he was knocked down by a car which was being followed by a police helicopter.
The car, a Fiat Punto, was being followed after it failed to stop for a police car on Friday night.
Police said it turned into Bishopton Road, in Stockton, where it knocked down a 17-year-old boy and collided with a lamppost.
The teenager suffered internal injuries and a broken leg. The driver, 21, was arrested for motoring offences.
The three people inside the car had to be cut free by the fire service, Cleveland Police said.
The teenager is said to be in a stable condition in hospital.