Six fire crews spent more than four hours battling a blaze in the middle of Norwich.
It happened shortly before 8.45pm on Monday, when emergency services were called to Mandells Court, between Princes Street and Waggon and Horses Lane.
Flat-fire-in-Norwich-city-centre (2)
Teams from Carrow, Sprowston, Earlham, Hethersett, Wymondham and Loddon were all called to help at the block of flats.
Flames and smoke could be seen pouring out the roof of the building, as firefighters used main and hose reel jets, breathing apparatus and an aerial ladder platform to put it out.
Norfolk Fire and Rescue group manager Emyr Gough said the block of flats was "fully enveloped in fire".
He added his colleagues had been "actively and aggressively fighting the fire to stop the spread".
Ambulances were also spotted at the scene, but Mr Gough said they were there only as a precaution.
"No persons have been seriously injured, ambulance are here just checking the residents," he said.
A spokesperson for the fire service confirmed the stop message was received at 12.58am this morning, after a thermal imaging camera had been used to check for hot spots.
An investigation is currently under way to determine the cause of the fire.
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