More than 40 firefighters were called to attend a fire in St Ives in the early hours of Saturday.
Crews from Huntingdon, Cambridge, Gamlingay, Chatteris, St Neots, Cottenham, Ely and Stanground, along with a crew from Potton in Bedfordshire, attended the incident, in Meadow Lane.
Crews were called to attend at about 4.15am.
A spokesman for Cambridgeshire Fire and Rescue Service said: "Crews arrived to find a fire inside two buildings and a high level conveyer belt. Wearing breathing apparatus, firefighters used four hose reels to extinguish the fire before returning to their stations by 8.45am.
The incident was later re-inspected."
An investigation determined the cause of the fire to be accidental.