At 8.02pm on Saturday (29) one crew from March and one crew from Chatteris were called to a fire on the A141.
Firefighters arrived to find a caravan on fire in a layby on Isle of Ely Way. They extinguished the fire using hose reels and returned to their stations by 9.15pm.
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.