At 3.26am on Friday (25) crews were called to a fire on Histon Road in Cambridge.
Around 50 firefighters, including crews from Cambridge, Cottenham, Papworth, Burwell, Linton and Huntingdon, along with crews from Newmarket and Bury St Edmunds in Suffolk, attended the scene.
Firefighters arrived to find a well-developed fire in a disused building.
Residents in the area were advised to keep their doors and windows closed as a precaution due to the smoke. A road closure was also put in place to allow crews to tackle the fire safely.
Update – 9am
The incident has been scaled back and most of the crews have now left the scene, however there will still be firefighters at the scene ensuring the fire is fully out and the area is safe.
An investigation will be carried out once the fire is fully extinguished.
Road closures may still be in place, so please check the latest info on @Cambs_Traffic on Twitter.
Update – midday
The fire is now out and the crews have left the scene. They will be making regular inspections of the site to ensure it is safe and any hot spots are put out.
The road is now fully reopened.
An investigation has confirmed the fire was started deliberately. Anyone with information should contact police by visiting www.cambs.police.uk to submit an online report or call Crimestoppers on 0800 555111.