One appliance and crew from Gerrards Cross and one from Windsor, Tinkers Lane attended, along with an officer.
The firefighters used one set of breathing apparatus and one hose reel. They also used an environmental pack to mop up the run-off water.
Police closed both carriageways of the road while the fire was being dealt with.
The Luton van was destroyed in the fire, and the incident was left in the hands of the police.