The huge fire broke out shortly after 1pm at the Speedibake factory, near to Ings Road Retail Park, in the centre of Wakefield.The town was covered in a cloud of black smoke as fire crews rushed to the scene. Witnesses also reported hearing 'explosions' coming from the fire.
At its peak, there were 20 fire engines and 140 firefighters at the scene.
Overnight the operation was scaled down and there are now eight fire engines working at the site, with two aerial ladder platforms (ALPs). Crews have also set up a water relay to feed to the two ALPs.
At 6pm on Saturday ,West Yorkshire Fire Service said they expected to be in attendance at the fire for another 24 to 48 hours.
A statement on its website said: "Please avoid the area to allow emergency services to deal with the incident."