Crews from March, Chatteris, Whittlesey and Wisbech were called to a fire in the roof of a three-storey building converted into flats along the High Street.
The MultiStar appliance also attended from Stanground, along with the Command Unit and support crew from Huntingdon.
About five or six people in the flats at the time of the fire self-evacuated before fire crews arrived.
Firefighters wearing breathing apparatus used two hose reel and a jet to extinguish the fire and returned to their stations by 3.59am.
Cause of the fire was deliberate.
Anyone with information should contact police on 101 or call Crimestoppers anonymously on 0800 555 111.