Police now believe that a fire started at a disused factory on Friday night could be a result of arson.
The blaze, at the old Seddon Packaging and Print building on Field Street, was caused when two fires were started inside the site.
Police said that extensive damage was caused to the building, which could have escalated to nearby residential properties.
They are now appealing for witnesses, or anybody who might have any information, to come forward and call Northamptonshire Police on 101, alternatively they can call crimestoppers on 0800 5555 111.
Six crews from across the county attended the fire at 22:38PM on Friday night and discovered a blaze on the first-floor of the factory.
The crews managed to confine the fire to the first floor, but the rest of the building suffered light smoke damage.
Crews from Kettering, Burton Latimer, Desborough, Corby and Wellingborough tackled the blaze.
Police said that the fire was started between 10PM and 11PM.