At 5.15am on Friday (12) one crew from Wisbech, along with crews from West Walton and Outwell in Norfolk, were called to a fire on Walton Road in Wisbech.
Firefighters arrived to find a fire involving a building used as a summer house and extinguished it using a hose reel. They returned to their stations by 6.35am.
The cause of the fire was deliberate. Anyone with information should contact police by visiting www.cambs.police.uk to submit an online report or call Crimestoppers on 0800 555111.