An area of a Hartlepool secondary school has been closed after work on the roof twice led to the building being evacuated.
The incidents happened at High Tunstall College of Science, in Elwick Road, Hartlepool, after smoke from the work set off the alarm.
School chiefs say the area was checked and it was found that smoke had set off the alarm and pupils were allowed back inside after being evacuated.
But staff and pupils were evacuated again after the alarm sounded for a second time before firefighters were called, and found the area to be safe to return.
Now the school has decided to close the D Block until the work is completed in around 10 days time.
A spokesperson from High Tunstall College of Science said: “At about 2pm yesterday, a fire alarm was set off within the college’s old D block, where extensive roof works are currently taking place.
“All students and staff were immediately evacuated, and school officers checked the building to discover smoke from the works had set off the alarm.
“Some time later, the alarms were triggered again and all children and staff were once again evacuated.
"The fire brigade attended the scene and deemed the building safe, and health and safety were informed.
“We have made the decision to close the D block building until the roof works are completed in approximately 10 days time, and the timetable is being re-organised to ensure learning is not disrupted.
“The college would like to stress that at no point was there any danger to any young person, and we are in the process of carrying out a full investigation into the incident.”
A spokesman for Cleveland Fire Brigade said: "By the time the service got there, the fire was out, but we used a thermal image camera to check everything.
"We sent two fire engines because it was a school."