The East Anglian Air Ambulance was called to the Tesco superstore in Swaffham on Tuesday afternoon after a woman collapsed.
The East of England Ambulance Service NHS Trust (EEAST) received a call just after 1pm to Castle Acre Road in Swaffaham to a report of a woman who had collapsed.
An ambulance crew, rapid response vehicle and East Anglian Air Ambulance were dispatched.
They treated a woman in her 40s who was conscious and breathing, who had suffered a serious head injury.
She was taken by land ambulance to Queen Elizabeth Hospital for further treatment.
Police closed Brocks Road during the incident and advised people to avoid the route.
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