A car, about 500m of straw stubble and hedgerow were deliberately set on fire in Chatteris yesterday morning.
Crews from March and Chatteris were called to the blaze in the open in Stocking Drove at around 11.33am.
Firefighters used hose reels to extinguish it and crews returned to their stations by 2.45pm.
The cause of the fire was deliberate, said a Cambs Fire spokesman.
Anyone with information about the incident should contact the police on 101 or Crimestoppers anonymously on 0800 555111.
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