The alarm was raised shortly after 4am and 12 fire engines from Lancashire and Greater Manchester – along with several specialist appliances – attended the incident at the at a single storey building located in George Street.
Firefighters used four breathing apparatus, three hose reel jets and an aerial ladder platform to bring the fire under control and successfully prevent it spreading to an adjacent mill.
One casualty was rescued and received precautionary checks from ambulance personnel.
By 7am, the crews with breathing apparatus had been withdrawn while external firefighting continued using specialist equipment.
Later on Saturday morning, a spokesman for the fire service said: "This incident is now being scaled back to eight fire engines, supported by a specialist stinger appliance and an aerial ladder platform."
Shortly before noon, that was reduced to four fire engines, an aerial ladder platform and a command support unit.
Mark Hutton, head of prevention and protection for Lancashire Fire & Rescue, later posted a dramatic drone picture of the scene, saying it provided "situational awareness that just can’t be gained from ground level.
"It also shows the Stinger hard at work piercing metal roofing and getting water on to the fire - ultimately helping preventing fire spread to adjacent mill," he added.