Hugh Sexey Middle School will be closed today and tomorrow due to yesterday's fire.
The Blackford school was evacuated at 10.20am after a fire broke out in an empty classroom. Devon and Somerset Fire and Rescue said the cause in an electrical cabinet was accidental and 80 per cent of the classroom and roof space has been damaged by smoke.
The electricity was turned off and oxygen-equipped firefighters from Cheddar, Burnham-on-Sea and other stations stripped tiles from the roof to get at the fire with hoses.
Head teacher Jenny Venning described the day as "extraordinary".
She said: "Smoke has affected a lot of the building and clearly 8 GDA and Miss D'Auria's room will need to be cleared and made good.
"However, the biggest problem is restoring the electricity so that we can get the school open and running as quickly as possible.
"The electricity cables coming into the school and those feeding electricity out to the school have all been very badly damaged and this is going to be a major piece of work."
Mrs Venning is meeting with the local authority to assess what can be done and further updates will be made at www.hughsexey.com.