Fire officers investigating the cause of a blaze which destroyed part of a school in Derby are considering whether it was started deliberately.
The damage at the 1,000-pupil Sinfin Community School, where 23 classrooms were damaged, will cost more than £10m to repair.
More than 70 firefighters were called to the blaze on Wednesday.
It was initially thought it was caused by an electrical fault in a drama room, but that has been ruled out.
Investigators now know the fire broke out in a storeroom, but still need to establish how it actually started.
It spread across 23 classrooms, kitchens, two computer rooms and a lecture theatre.
Police are also investigating claims that three people were seen running away from the site just before the fire took hold.
GCSE English coursework was damaged and temporary classrooms will be brought in to accommodate pupils in the run up to exams.
Daniella Salt, aged 16, told the BBC how her English coursework was destroyed in the fire.
She said: "We were just watching it... but then as we started to watch the fire I was thinking what's going to happen to my future?
"We might have to do it again according to a couple of the teachers.
"My maths has already been sent off, so that's alright."
The school will stay closed until the end of the week, but it is hoped some lessons will resume on Monday and alternative venues such as church halls in the area may be used.