A fire service spokesman said the alert came in of the 'severe fire' just before 7pm, and eight fire engines from Lewes, Roedean, Brighton, Hove, and West Sussex were called to Donald Hall Road.
The spokesman said: "A man was rescued from the flat and taken to hospital and treated for smoke inhalation. Another four residents were given fire survival guidance and were assisted out of the building.
"Crews used ten breathing apparatus, one jet hose and two hose reel to extinguish the fire."
Residents caught up in the fire were 'advised to stay put' in the six-storey building by 'various specialist officers', as confirmed by the fire service.
The spokesman also revealed that the fire broke out from a bedroom of one of the flats in the building, which pictures suggest was in the second floor.
Roads in the area were reportedly blocked, whilst pedestrians were diverted to another path.
The fire service spokesman said the incident was controlled at 8.21pm and crews carried out welfare and home safety checks on all remaining residents.
It added: "Officers remain on the scene today [Saturday]. whilst fire investigation procedures take place."