Police want to trace an injured man seen getting dragged from the wreckage of a car which smashed into a house.
The mystery person and the man who removed him from the vehicle were quickly collected by another car before emergency services arrived.
The house suffered substantial damage following the early-morning incident although no-one in the property, including two children sleeping on a downstairs sofa, were injured.
Checks with local hospitals have so far failed to trace the injured man, who had blood on his face, and officers want to trace him as a matter of urgency.
The incident took place at around 1.50am today when Cleveland Police received a call that a silver Renault Megane had collided with the front of a house in Rosslare Road, Roseworth, Stockton.
A member of the public is said to have witnessed a male, believed to be aged in his late teens, being dragged from the passenger side of the silver Megane.
Another man who is described as being aged in his 20s with black hair and wearing a grey tracksuit dragged him from the car.
Police believe that they were then both collected by a black Renault Megane which drove them away from the scene.
Detective Sergeant Kenneth Clar,k from the Stockton Volume Crime Team, said: “We would like to trace the passenger of the silver Renault Megane as a matter of urgency so that we can check on his welfare.
“We are also keen to hear from anyone who may know the identity of the man at the scene in the grey tracksuit as he may be able to assist with tracing the passenger."
“Anyone with information is asked to call Cleveland Police on 101. Information can be passed anonymously.”