Fifteen fire engines and around 95 firefighters and officers were called to a fire at a school on Craven Walk in Clapton Common in Hackney last night.
The basement, ground floor and first floor were gutted in the fire as well as a small part of the second floor in the three and four storey building.
There were no reported injuries.
Station Manager Nicola Lown was at the scene, she said: "The ground floor partially collapsed into the basement leading to hazardous conditions. Two fire rescue units were also on the scene and their equipment was used to shore up the ground floor. This enabled crews to wear breathing apparatus to gain better access to the fire in the basement."
The Brigade was called at 2356 and the fire was under control 0653. Fire crews from Stoke Newington, Tottenham, Homerton, Hornsey, Holloway fire stations and other surrounding fire stations were at the scene.
The cause of the fire is under investigation.