Crews from Cambridge and Huntingdon were called to a rubbish fire, 20 ft by 10 ft, in a derelict building in Histon Road.
Firefighters wearing breathing apparatus used a hose reel and two jets to extinguish the fire in a large rubbish pile.
They also used a thermal imaging camera to look for hot spots, and a positive pressure ventilation fan to clear the smoke, before returning to their stations by 8.08pm.
Cause of the fire was deliberate.
Anyone with information should contact police on 101 or call Crimestoppers anonymously on 0800 555 111.