A fire has ripped through classrooms and caused extensive damage at an Auckland intermediate school.

Emergency services were called to Auckland Normal Intermediate School in Mt Eden about 2.30pm.

The fire is believed to have started in the school hall, where people were said to be working on the roof.

Smoke could be seen billowing across the nearby village, with flames erupting from the roof of the building.

A nearby resident said smoke was thick throughout Mt Eden Village and as far as Auckland Grammar on Mountain Rd.

"I can also smell the smoke here in Three Kings," she said.

At least six nearby houses were also evacuated.

A Fire and Emergency spokesman said at the peak of the fire, there were 22 crews and approximately 90 firefighters working to curb the blaze.

A cherry picker was also used to tackle the blaze.

He said the building was approximately 70m by 30m and was "well involved" in fire.

He said there was significant damage to the building.

A St John spokeswoman said one man, a worker who was inside the school when the fire broke out, was treated for minor smoke inhalation.

Principal Jill Farquharson posted an alert on the school's website on this afternoon saying, "Earlier this afternoon a fire broke out in the school hall causing significant damage not only to the hall, but adjoining buildings.

Currently students remain on school holidays, with the first day back on Tuesday, January 29. Photo / Rosie Gordon

"We are still in the early stages of working with other agencies to determine the impact on the school and how, if any, it will have on the opening of the school on the 29th of January," she said.

"This is a timely reminder to everyone that emergencies can occur at any stage and the school has robust plans to deal with a range of situations.

"All staff that were on-site at the time were evacuated quickly and safely. I would like to personally thank you for your ongoing support and we will keep you updated."

A former student James Tapp said it was pretty sad watching the fire at his old school.

"It's been a school that has a lot of local school children go through it and there are a lot of memories for a lot of people within those rooms," he said.

At the peak of the fire there were 22 crews and approximately 90 firefighters working to curb the blaze. Photo / Michael Craig

Tapp said the fire looked as if it had started in the main hall and spread towards the science classrooms, the computer labs, and the music and drama rooms.

Poronui St was closed at the intersection with Mt Eden Rd due to the fire and police were assisting with traffic control

Auckland Normal Intermediate School (ANI) is a co-educational school catering for students aged 11-13 years.

Currently students are on school holidays, with the first day back on Tuesday, January 29. Today was a teacher only day, so there were staff present at the school.

“There has been no confirmation of injuries yet, there are a few St John ambulances at the scene, but nothing has been confirmed. There are over 20 people standing around the scene, one of which is a former student who said its devastating to see what has happened to his former school.”