Two men are still in hospital following a crash at Carbrooke when a car hit a tree.
The collision involved a grey Volkswagen Polo and happened at about 11.20am on Friday, June 22, on the B1108 Norwich Road close to the B1077 junction.
The Polo was travelling towards Watton when it left the road and officers are keen to speak with the driver of a black car seen travelling in the area around the time of the accident.
An 18-year-old man, who was the passenger, remains at Addenbrooke's Hospital, Cambridge, with serious, head, back and stomach injuries. He is in a critical but stable condition.
The driver, also an 18-year-old man, was taken to the Norfolk and Norwich University Hospital and is in a serious but stable condition with head, chest and back injuries, according to a Norfolk police spokesman.
Anyone with information about the crash or the driver of the black vehicle should contact PC Matt Gouldsmith at Wymondham Roads Policing on 101.
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