The fire at the former RAF site - the third in three weeks - was started deliberately.
Fire crews were called to tackle a blaze at a former airbase - the third attack in three weeks.
A crew from Ramsey arrived at the former RAF Upwood site at 6.46pm yesterday (May 5) to find a building on fire.
Firefighters had to use a hose reel to extinguish the fire, before returning to their station by 7.30pm.
The fire is believed to have been started deliberately.
Less then three weeks ago crews from Cambridgeshire Fire and Rescue Service were called to the site April 17 to reports of a large bonfire containing wood, tyres and rubbish.
A second crew from Huntingdon and one crew from Ramsey were called to a building fire at site on April 18.
Firefighters arrived to find smoke coming from a derelict building and had to use a hose reel and drags to extinguish the blaze. They believe both fires had been started deliberately.
Anyone with information should contact police by visiting http://cambs.police.uk to submit an online report or call Crimestoppers on: 0800 555111.