Police are appealing for witnesses to a three-vehicle crash at Walsoken in which four people were injured.
It happened at 3.20pm on Saturday on the B198 Lynn Road and involved a blue Honda Civic, a blue VW Tiguan and a yellow HGV.
A woman passenger in the Honda, aged in her 60s, was taken by air ambulance to Addenbrooke’s Hospital at Cambridge with life-threatening injuries.
The driver of the Honda, a woman in her 30s, suffered serious back injuries and was taken to the Queen Elizabeth Hospital (QEH) in King’s Lynn, and later transferred to the Norfolk and Norwich University Hospital.
A young girl in the Honda suffered a head injury and was taken to the QEH.
The driver of the Tiguan, a woman in her 40s, suffered minor injuries and was treated at the QEH and discharged.
Officers also want to hear anyone with dash cam footage. Call PC Chris Webb at Norfolk Police on 101.