At 10.42pm on Friday (14) crews were called to a fire on Mercers Row in Abbey ward, Cambridge.
Firefighters arrived to find a well developed fire in a two-storey industrial unit, called Funky Funhouse.
More than 40 firefighters, including crews from Cambridge, Cottenham, Burwell, Chatteris, Gamlingay, Linton, Ely and St Ives attended the scene.
Crews used hose reels and jets to fight the fire from the outside to stop it spreading to other buildings. The Multistar aerial appliance was also used to tackle the fire from above.
Crews remained at the scene throughout the night to ensure the area was safe and the fire was fully extinguished.
A fire investigation is now underway to determine the cause of the fire.
Update - 3.30pm, Saturday April 15
The investigation has been completed and the cause of the fire has been confirmed as deliberate. Anyone with information should contact police on 101 or Crimestoppers on 0800 555111.
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