Firefighters from Hamsphire and Isle of Wight Fire and Rescue Service were called at 03.25 pm to Cherry Blossom Court, Sultan Road, Portsmouth after a fire broke out.
Appliances from Southsea and Cosham used breathing apparatus, high power jet hose and one hose reel to extinguish the fire.
One casualty was treated by HIOWFRS at the scene for smoke inhalation and later handed over to South Central Ambulance Service.
A full fire investigation is now underway.
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