A woman, critically injured after being hit by a marked police van, was flown to hospital by the Duke of Cambridge on his final shift with the East Anglian Air Ambulance.
The van struck the woman, who was on foot, on the B1135 Wymondham Road at Hethel at 22:20 BST on Thursday.
Officers were responding to a 999 call relating to a missing woman when the crash occurred.
Prince William and his team flew her to Addenbrooke's Hospital in Cambridge.
The woman, aged in her 50s who was injured in the crash, was the same woman whose safety police were alerted to, Norfolk Police said.
No-one else was hurt in the crash.
An East Anglian Air Ambulance (EAAA) spokesman said: "The EAAA crew, which last night included William, attended an incident south of Norwich which involved a road traffic collision-related injury.
"A patient was treated at scene for severe head injuries then treated at Addenbrooke's Hospital."
The Duke of Cambridge is stepping down from his role as a pilot with the EAAA to take on more royal duties on behalf of the Queen and Duke of Edinburgh.
The case has been referred to the Independent Police Complaints Commission.