Fire crews from across West Yorkshire were called to to reports of a derelict building on fire on Birkdale Road, Dewsbury.
The site is of the former Wheelwright Grammar School.
The West Yorkshire Fire and Rescue Service have said crews will remain at the scene throughout the afternoon to monitor hotspots and the structural safety of the building.
There were no persons involved in the incident.
The West Yorkshire Fire and Rescue Service have said crews will remain at the scene throughout the afternoon to monitor hotspots and the structural safety of the building.