Arsonists set fire to large quantities of rubbish and tyres in Elm.
Wisbech firefighters were called to Kirkhams Lane, on Saturday just after 9.30am.
Two separate fires had been started about 150m apart, which were put out using hose reel jets.
The crew returned to its station by 11.20am.
Anyone with information is asked to call police on the 101 number.