Emergency crews were called to the scene at Sanders Lodge Industrial Estate in Rushden at about 6.30am on Friday.
A number of road closures have been put in place, and local residents are being advised to avoid the area and keep their windows and doors closed.
Northamptonshire Fire and Rescue Service (NFRS) said it is receiving cross-border support from Bedfordshire Fire and Rescue Service (BFRS) and anticipates crews will remain at the scene “for the rest of the weekend”.
NFRS said the fire involves a “large quantity of plastic”.
Ten fire engines have been mobilised, as well as three turntable ladders, two water bowsers and a high-volume pump.
A NFRS spokesperson said: “Due to the large smoke plume coming from the blaze, we are asking people nearby to avoid the area and keep their windows and doors closed.”
No patients have been reported at the scene.
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Northamptonshire Police is also providing support and has implemented a number of road closures, including:
• Full closure of all slip roads at J16 of the A45, both eastbound and westbound (the A45 itself is open past the scene).
• Ditchford Road, between the junction with Mill Road and the A45.
• Northampton Road at the junction with Wellingborough Road.
• Wellingborough Road at the junction with Washbrook Road.
A force spokesperson said: “Please avoid these areas and find alternative routes. Thanks for your patience while we and blue light partners deal with this incident.”
