A mother and baby were rescued from a first floor flat in Kibworth by the Fire Service, after a blaze that is believed to have been started deliberately.
The two had to be rescued by ladder from a first floor window, during the fire at Glebeland, Kibworth Harcourt, in the early hours of Saturday, February 25.
Leicestershire Police said a 27-year-old man has subsequently been arrested on suspicion of arson with intent to endanger life.
Police said anyone with information on the incident should contact them on 101, quoting incident 17*81428.
Fire crews from Market Harborough, Wigston and Central in Leicester attended the fire, after a 999 call at 00.18am, early on Saturday morning.
As fire crews sped to the scene, a woman at the flat was given fire survival guidance over the phone by a fire service operative.
The fire was concentrated in the hallway of the flat, so the woman and her young child were rescued by ladder.