The blaze broke out at Company Coaches on Kirkhaw Lane in Ferrybridge, Knottingley just before 12.40pm yesterday.
An eye witness reported seeing flames reaching up to 40ft high.
One fire crew from Pontefract Station is on site this morning and one large jet has been on the premises throughout the night.
West Yorkshire Fire and Rescue Service said the building involved is a 30m by 50m commercial coach storage depot.
Eight fire engines as well as specialist officers from around the county were scrambled to the scene, next to Ferrybridge Power Station, yesterday.
Hoses stretching hundreds of metres were used to bring water to the depot and help get the fire under control.
The fire service temporarily closed all the surrounding roads.
And firefighters used large water jets to dampen the area around the fire, as acetylene cylinders were involved.
One eye witness who works near the warehouse said: “There was no explosion or anything like that, but there were flames shooting 30 or 40ft up in the air.
“They were really high and there was a lot of smoke.”
Plumes of smoke were seen billowing over the nearby power station, close to the M62 and A1M motorways.
No one was evacuated or injured in the blaze.