At 1.07am on Wednesday (27) crews were called to a fire on Cobden Street in Peterborough city centre.
Crews from Dogsthorpe, Stanground, the Peterborough Volunteers Fire Brigade, Yaxley, Whittlesey, and Thorney, along with a water carrier from Ramsey and the incident command unit from Huntingdon, attended the scene.
Firefighters arrived to find a well-developed fire in a factory unit, measuring around 50 by 10 metres. Using jets and hose reels they extinguished the fire and returned to their stations by 8am.
There are no casualties at the scene.
An investigation is now underway to determine the cause of the fire.
The investigation has determined the fire was started accidentally.