A neighbour raised the alarm after a fire broke out in a Huntingdon flat on Sunday morning (June 8).
The neighbour smelt smoke coming from a flat below him in Elm Close at about 12.30am and called 999.
Huntingdon firefighters extinguished the fire, which was started by “smoking materials”.
People in the flat had fled their home by the time the fire crews arrived.
Station commander Kevin Napier, fire investigator, said: “We believe it was smoking materials that caused this fire and we would urge all smokers to take simple steps to reduce their risk of fire.
“Never smoke in bed or in an armchair if you are feeling sleepy, regularly empty ashtrays and always extinguish smoking materials responsibly.
“Most importantly, always make sure you have a correctly fitted working smoke alarm on each floor of your property and test it regularly.”