A man is fighting for his life in hospital after a horror smash.
The man - in his forties - was left with life-threatening injuries following the collision at the junction of Milbank Lane and Thorntree Road, in Thornaby.
Emergency services - including an air ambulance - were called to the incident, which happened at about 5.40pm today.
A blue Vauxhall Corsa and a dark blue BMW 320 series convertible collided with each other and police say they are looking for the driver of a black Volkswagen Golf, which was following the BMW at the time.
The driver of the BMW suffered life-threatening injuries to his head, chest, pelvis and leg, and was airlifted to James Cook University Hospital, where he arrived in a critical condition five minutes later.
A spokesman for the Great North Air Ambulance said: "At 17.45, the Great North Air Ambulance Service responded to a multi-vehicle collision in Thornaby.
"North East Ambulance Service were on scene when our doctor-led trauma team arrived.
"They assessed and treated a male patient before flying him to James Cook University Hospital."
A statement from Cleveland Police read: "Police have closed the road between Milbank Lane and Thorntree Road in Thornaby following a collision between a blue Corsa and a dark blue BMW 320 series convertible at 5.40pm.
"The driver of the convertible was taken by air ambulance to James Cook University Hospital suffering from internal bleeding.
"The driver of the Corsa had minor injuries.
"Police want to trace the driver of a black Volkswagen Golf which was following the BMW.
"Anyone with any information should contact police on 101.
"The road is not expected to re-open for around two hours."