More than 100 firefighters are tackling a blaze at Dalton mills used as a film location for hit shows such as Peaky Blinders and Downton Abbey in Keighley.
Footage on social media shows flames engulfing the Grade-II listed building, Dalton Mills in Dalton Lane, Keighley.
West Yorkshire Fire and Rescue Service said 20 pumps were called out just before midday.
The blaze started on the ground floor and has spread throughout the building.
Currently, there are no reported injuries.
West Yorkshire Police is urging people living nearby to keep their windows and doors closed and say people should avoid travelling to the area.
The police, ambulance, Yorkshire Water and Environment Agency are all on the scene.
Dalton Mills dates back to the 19th century and was once the largest textile mill in Yorkshire, employing over 2,000 workers.
There is a police cordon in place and some roads have been closed.