The fire at Mirfield Prestige in Huddersfield Road initially involved a caravan and car, but a building and four more vehicles and caravans were engulfed as the flames spread.
Crews from Mirfield, Rastrick, Cleckheaton, Huddersfield, Ossett, Dewsbury and Odsal were at the scene from 8.24pm last night.
The response involved nine pumps and an aerial appliance.
Seven large jets, four breathing apparatus sets and three hose reels were in use when the fire was at its height.
Other specialist appliances and officers from around the county also gave additional support.
Afire service spokeswoman this morning said the number of crews had now been scaled down.
Three pumps and one aerial appliance remain on site.