Firefighters are scaling back its operation after crews spent the whole of the morning tackling a factory fire.
Ten fire engines were called to the incident at Ryburne Mills in Halifax.
Six pumps were called 3.51am this morning.
The fire was in the basement area of a window manufacturing company Ryburne Windows and the ground floor is also involved.
Plumes of smoke was given off and although it was not thought to be harmful residents in the vicinity of Hanson Lane, Queens Road and Gibbet Street are advised to keep doors and windows closed.
A spokesperson for West Yorkshire Fire and rescue Service said: " There are still two fire engines in attendance at Ryburn Mills in Halifax after a large fire overnight.
"Crews are damping down. A big thanks to the local community and our partner agencies for their support as we tackled this incident."
Appliances from Halifax, Illingworth, Rastrick, Cleckheaton, Odsal and Fairweather Green are in attendance along with a number of supporting appliances with specialist equipment.
Firefighters used foam and water to tackle the blaze.
Hanson Lane in Halifax was closed between Queens Road and the junction with Thrumhall Lane because of the incident.
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