Five fire engines plus the aerial platform are currently attending a serious blaze at a school site in Great Sutton which has led to some homes being evacuated.
Cheshire Fire and Rescue Service received reports at 5.09pm of a 'well established' fire at Saint Saviour's Catholic Primary School in Seacombe Drive.
A building measuring approximately 100 metres by 50 metres is involved and it has since been confirmed it is a disused nursery that was due to be demolished.
Fire spokeswoman Sarah Dornford-May said five fire engines are on scene from Chester, Ellesmere Port, Powey Lane, Runcorn and Bromborough plus the aerial platform. Ground monitors are in place with powerful jets aimed at the blaze from the exterior.
The aerial platform is just about to come into operation. There are no persons unaccounted for. And the cause of the blaze is not known at this stage.
Pictures posted on social media show large clouds of grey smoke billowing from the source of the blaze against a blue sky.
Cheshire Police are on scene and advising residents to keep their windows closed. Officers are assisting with traffic management. There are road closures in place on Charter Crescent and Ringway which both adjoin Seacombe Drive.
All school children are now on their six-week holiday.
Group manager Mike Anderson of Cheshire Fire and Rescue Service said the fire had broken out in a disused building at the back of St Saviour's School which had been earmarked for demolition anyway.
He explained there had been initial concerns because asbestos had formed part of the building but it was later confirmed the asbestos had been removed from the site just two to three weeks ago.
A cordon has been put in place on Seacombe Drive and a limited evacuation of nearby homes was taking place because the smoke coming from the scene was regarded as hazardous. Both measures are likely to remain in place for the next couple of hours.