This article was reproduced with the kind permission
of the British Broadcasting Corporation
19 November 2007, 18:59 GMT
Crews were called to Preston Plastics in Lancaster Road, Out Rawcliffe, in the early hours of Monday.
A fire service spokeswoman said 25 houses near the site were evacuated following the fire.
She said the factory had been extensively damaged in the blaze, which started in a storage area. No-one had been in the building.
A police spokesman said the fire triggered Operation Merlin - an emergency services plan which comes into effect during major incidents.
The site was being contained as there were two acetylene cylinders at the scene.
The fire service said water was pumped from the River Wyre to help fight the blaze.
People living in the nearby area who have not been moved away are being urged to stay indoors and shut their windows and doors.
Those who had to leave their homes were allowed back on Monday afternoon.