A large fire in a disused school building might have been started deliberately, firefighters say.
Fire crews were called to The Grange School and Sports College on Tower Road in Warmley, South Gloucestershire, at 00.30 GMT.
At one point 55 firefighters were dealing with the blaze that damaged about half of the buildings.
Avon Fire and Rescue Service said the cause of the fire "was thought to be deliberate ignition".
The school closed six years ago and no-one was injured, Steve Quinton, the service's group manager said.
At the height of the blaze, crews from 11 different fire stations from Bristol, South Gloucestershire and North Somerset were at the scene battling the flames.
Digitech School, which shares the same site, was closed for the day while fire crews remained at the scene.
Its principal Lis Jolley said: "I can confirm that the Digitech Studio School building has not been damaged in any way. But, unfortunately because of the proximity of the fire, the school will remain closed today for all staff and students, with the hope that the school will reopen tomorrow as normal."
The Grange School closed in 2016 after being placed in special measures.
The site had been earmarked for redevelopment by South Gloucestershire Council.