An investigation is underway following a two car collision on the A68 near Toft Hill, Thursday 13th September.
The incident, involving a green Vauxhall Astra and Silver Kia, took place at about 7.30am, between Witton-le-Wear and Toft Hill.
One male driver was airlifted to James Cook University Hospital, in Middlesbrough, with injuries described as critical.
The other male driver and a teenage boy were taken to the same hospital with serious injuries.
The A68 was closed for nearly seven hours to allow investigation work to be carried out.
Police are keen to speak to anyone who witnessed the incident and particularly anyone with any dash cam footage from between 7.20am and 7.30am.
Witnesses should call Durham Constabulary on 101, quoting incident number 55 of September 13.
