Police have appealed for witnesses to help with an investigation into an horrific road smash in which a teenager died.

Karl Sutcliffe died when the Peugeot 309 he was driving collided with a marked police vehicle on the A689 Coundon bypass, near Bishop Auckland, County Durham.

The 19-year-old, of Walker Drive, Woodhouse Close Estate, Bishop Auckland, was flung from the car when it hit the BMW patrol car.

He was certified dead at the scene by a police surgeon. Investigating officers now want to speak to a man who may have witnessed the accident, shortly before 10.30pm on Monday night.

The man, thought to be in his 50s, wore a maroon or red shirt, and stopped to help officers in the patrol car.

Police are also urging the drivers and occupants of two cars, seen travelling towards Bishop Auckland just before the crash, to come forward.

One was a grey car, possibly a Renault Clio, the other was a white Vauxhall Nova with a bright visor over the front windscreen.

Three of Karl's friends, passengers in the Peugeot who fled the scene after the collision, have answered a police appeal urging them to come forward.

Two voluntarily visited police on Tuesday and the third walked into Bishop Auckland police station yesterday (WED).

PC Neil Fuller, 27, a front seat passenger in the patrol car, had to be cut free from the wreckage by firefighters.

He was taken to Darlington Memorial Hospital for treatment to leg injuries and released the next morning.

The driver of the police car PC Gary Emerson, 41, was also taken to the hospital and released after he was treated for shock and bruising.

A full scale investigation was immediately launched into the accident, which will be led by Detective Chief Inspector Bruce Turnbull.

Durham Constabulary passed details of the incident to the Police Complaints Authority to oversee the inquiry and it approved Det Chief Insp Turnbull as the leading officer.