The fire at Princewood Road in Corby now appears to be under control after crews from across the county managed to quell the flames.
Northants Fire and Rescue have not yet revealed the exact location of the fire although it is believed to have broken out in a yard at Guaranteed Asphalt in Princewood Road.
One nearby worker, CJ Redmond Milne who works at Spirol Industries said: "There was another big fire close by not long ago.
"You don't expect lightning to strike twice."
Princewood Road is closed from Mademoiselle Deserts to the far end of the road and is expected to be so for at least four or five hours.
There are six pumps in attendance from Corby, Kettering, Oundle and Thrapston. The blaze broke out just after 12.30pm today.