At 7.26pm on Friday (24) one crew from Papworth and one crew from Gamlingay were called to a fire on High Street in Cambourne.
Firefighters arrived to find a fire in the open and extinguished it using a hose reel. They returned to their stations by 8.30pm.
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.