Crews from Ramsey and Huntingdon were called to a large quantity of unknown rubbish well alight next to a derelict building at RAF Upwood.
Firefighters wearing breathing apparatus used a hose reel to extinguish the fire and returned to their stations by 5.03pm.
Cause of the fire was deliberate.
Anyone with information should contact police on 101 or call Crimestoppers anonymously on 0800 555 111.
Cambridgeshire households told to prepare for flooding
Heavy rainfall has led to flood alerts being issued across Cambridgeshire.
1,000 homes in Cambridgeshire left without power
Over 1,000 homes in Cambridgeshire have experienced a power cut.
Warning after spate of keyless car thefts
A warning has been issued following multiple thefts of keyless vehicles across the region.
Chelsea Flower Show display to relocate to Addenbrooke's
A Chelsea Flower Show display will move to Cambridge after the show.
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