An air ambulance was called to an incident in Sheringham.
A spokesman for the East of England Ambulance Service said: "We were called at 11.02am on Friday, January 17 with reports of a person in cardiac arrest in St Peters Road, Sheringham.
"We sent a rapid response vehicle, community first responder, one ambulance and the East Anglian Air Ambulance. Crews are still at the scene."
A spokesman for the East Anglian Air Ambulance said: "We were dispatched to a medical emergency in Sheringham at 11.46am."
A fire crew from Sheringham helped the police, from about 11.50am, a spokesman for Norfolk Fire and Rescue Service said.
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