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.
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