The East Anglian Air Ambulance with a crew including Prince William was called to help a woman who collapsed in Mildenhall.
Paramedics were called at 8.30am to treat the woman who was in cardiac arrest.
She was taken by land ambulance to the Norfolk and Norwich University Hospital in a critical condition.
The East of England Ambulance Service sent a rapid response vehicle, two ambulance officers and an ambulance crew.
The air ambulance (pictured) landed in the Girton Close area.