Six firefighters wearing breathing apparatus were fighting a blaze at a bungalow in Burgess Hill this morning (Monday).
The incident occurred in Meeds Close, off Station Road, close to the town centre at 11.26am.
West Sussex Fire and Rescue Service said two members of the public were being treated for smoke inhalation at the scene.
Four fire engines were there from Burgess Hill, Haywards Heath and Crawley. Three hose reels were being used to bring the blaze under control with six officers wearing breathing apparatus fighting the fire.
A spokesman for the fire service said the cause of the fire was thought to be accidental at this stage.