Police investigating on following the fire at a flat in Arbury over the Bank Holiday weekend.
The incident, which is thought to have been started deliberately, happened in Carlton Way, Arbury, at about 3.30pm on Sunday.
Police attended and assisted while around 40 firefighters from Cambridgeshire and Suffolk extinguished the blaze.
One person was taken to hospital as a precaution and a number of others were treated by the ambulance service at the scene for smoke inhalation.
Officers are treating this as an isolated incident and a joint investigation is underway between the police and the fire service.
Detective Inspector David Savill said: "The fire has disturbed the lives of those living in the area and we are working to establish the full circumstances around what took place.
"I am keen to hear from anyone who may have heard or seen anything in the area at the time, particularly anybody acting suspiciously or leaving the flats in a hurry."
No arrests have been made. Anyone with information is urged to call 101 or report online via www.cambs.police.uk/report quoting crime reference number 35/30636/20.
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