Firefighters were called to a house in Lings, Northampton, after a blaze broke out in the early hours of today (Tuesday, 12 September).
Northamptonshire Fire and Rescue Service were called to the fire in East Paddock Court at about 3.50am. Four fire crews attended from Moulton, The Mounts, Mereway and Wellingborough.
One man was taken to hospital after being rescued from the property by firefighters. He is described as being in a critical but stable condition.
Detectives from Northamptonshire Police have been at the scene of the blaze throughout the day and conducted house to house inquiries in the area.
Det Sgt Johnny Campbell, from Northampton CID, said: "Our Fire Service colleagues have finished their investigation and they are satisfied that the fire was started accidentally and there is nothing to indicate foul play.
"They also want to thank the public in the immediate area for their tremendous co-operation and assistance today."