Firefighters have been tackling a blaze in Sywell for more than three hours.
Black plumes of smoke and a blazing fire has been rising from an industrial unit off Wellingborough Road, in Sywell, since about 12.45pm this afternoon (Tuesday).
Eyewitness Rachel Noding works at 'Seriously Helpful Marketing' in Hall Farm, in Sywell Business Park, next door to the industrial unit which has caught fire.
Rachel, who was evacuated by her company landlord, said: "As far as I know we are all out now.
"We were evacuated about 45 to 50 minutes after the fire started.
"I didn’t notice a smell so much but the smoke was black and then closer to the buildings it was white and orange."
Northamptonshire Police have closed several nearby roads while emergency services deal with the incident.
Meanwhile, Wellingborough Borough Council has advised residents to keep their windows shut for health and safety reasons.
Rachel added: "There were a lot of mini explosions to start with as we think it was a unit containing fridge freezers, and it was hot.
"[I] could feel the heat and the ash was raining down on us from our car park. There was no fire alarm or evacuation alarm, though."
It has not yet officially been confirmed which unit was on fire but this newspaper has approached Northamptonshire Police for a comment.
Lynn, who also works nearby and wanted to keep her surname anonymous, said: "It literally sounded like fireworks, I said to my boss: 'why would someone be setting fireworks off during the day, no one can hear them?'"
She went on to describe the sounds coming from the unit as "popping and pinging" noises and she said she saw corrugated parts fly off the roof once the flames took hold of the building.
And, just a short while afterwards, she described the building turning into a "ball of flames."
Opening times at Beckworth Emporium, Overstone Manor, The Worlds End and The Horseshoe pub are all unaffected.