The fire happened at a factory between Phoenix Parkway and Bangrave Road in Corby.
At its height there were ten pumps in attendance and it's believed fire fighters will be on the scene for the rest of the day and into tomorrow.
No-one is thought to have been injured in the blaze.
It's unclear at this time what caused the fire.
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Dry overnight, rain by tomorrow afternoon.
Dry with clear spells overnight, cool in rural areas.
"She tried to take hold of the knife to stop him. He told her not to shout out and scream and get on her knees and beg."