More than 70 firefighters have been tackling a fire at a Derby school.
Over 20 classrooms were destroyed in the blaze
Twelve fire engines and a high-rise appliance went to the blaze at the 1,000-pupil Sinfin Community School.
Head teacher Steve Monks said most of the main school block was damaged in the fire. The fire is thought to have started in a drama room.
The blaze began late on Wednesday afternoon, but a fire and rescue spokesman said the school was still "well alight" into the evening.
Mr Monks described seeing the fire from the road as he drove to the school.
"I was very worried when I pulled up as I could see the flames licking the roof of the building and I knew then it was a serious incident," he said.
The head teacher added that 23 classrooms and 2 computer rooms, including one containing the main server for the school, had been destroyed but no one was injured.
The cause is being investigated by Derbyshire Police and Fire and Rescue teams.
A youth worker who was in the drama room with a group of students after school, reported seeing smoke from the upper reaches of the room.
'Millions of pounds'
Mr Monks said some stage lights may have overheated and caught fire.
GCSE English coursework may also have been damaged in the fire and temporary classrooms will have to brought in to accommodate pupils in the run up to exams.
Repairs will probably run into "the millions of pounds," according to Mr Monks and the school will not be up to capacity until after Easter.
Officials said that the school would be closed on Thursday and is expected to remain closed for the rest of the week.