A major fire has erupted at Herdman's Mill at Sion Mills in Co Tyrone.
Nine fire appliances and 63 firefighters are at the scene along with a specialist high reach pump to tackle what has been described as a "significant fire".
The fire erupted around 2pm and quickly spread to the entire ground floor of the building.
Area Commander Maurice Rafferty, of the Northern Ireland Fire and Rescue Service said: "Crews at the scene currently report the fire as being contained, but are likely to remain on site for a considerable time to damp down isolated spots.
"The cause of the fire is as yet undetermined. No injuries to members of the public, or firefighters attending, have been reported.
"Crews are likely to remain on scene for a considerable time to prevent further fire spread."
The site was acquired by Margaret Loughrey after she won £27million on the lottery.
She bought the derelict mill to save it from being turned into a bio-waste plant as well as the surrounding land and sports pitches.