Fire crews from across the county raced to a fire at a recycling centre near Finedon last night (Monday).
A blaze at Suez Recycling Centre in Sidegate Lane started at about 10.20pm after a 50m by 20m building building went up in flames.
By 1am this morning eight fire appliances and more than 30 firefighters were at the scene tackling the fire.
A Northamptonshire Fire and Rescue Service spokesman said firefighters were still at the recycling centre but that most of the fire had been put out.
Sidegate Lane was closed but re-opened with traffic control measures in place at about 8am.
Nearby residents were advised to keep doors and windows closed as a precaution.
The cause of the fire is not yet known.