Firefighters are still tackling a blaze at Pagefield Mill.
The fire broke out at the derelict building in Swinley just after 4pm afternoon (Saturday) but is now under control.
Three fire engines were initially attendance but the operation has since been scaled back to two.
Images taken by resident Gaz Parkinson, earlier today, showed flames coming from the roof of the building.
Fire officer Paul Duggan said "All residents in the area should keep their windows and doors closed but the air is safe."
Crews, who have been fighting the flames from above have now moved inside the building to gain access to the fire from inside.
Eyewitnesses reported seeing police wearing masks in the area going from door to door to deliver safety messages to residents.
Paramedics were also at the scene.
Mesnes Park has been closed and the area surrounding the building is cordoned off. Road closures have been removed.
According to one onlooker, "extensive damage" has been caused to the roof and large sections have "collapsed".