An East of England Ambulance Spokesman said they were called at 11.38am and the air ambulance was also called.

A man in his 90s and another woman in her 40s have also been taken to hospital.

A spokesman for Norfolk Fire Service said it was a fire in a first floor flat. The fire broke out in the living room and the rest of the flat and the stairwell was smoke-logged.

Police confirmed that three people were within the property – a man and a woman were treated for smoke inhalation and a second woman was taken to the Norfolk and Norwich University Hospital in a serious condition.

The property was sealed off while police and fire investigators carry out initial inquiries to establish the circumstances of the fire.

By 2.30pm, the calm had begun to return to the residential neighbourhood, although officers are still working inside the building.

A neighbouring resident, who did not wish to be named, said: “There were five police cars, four paramedic cars and two ambulances. We saw the smoke and there were a lot of people out there watching.

“We were not sure if it was a car fire at first, until we saw the flames out of the window.”