Mindless vandals have targeted New Zealand's only rural special needs school, breaking windows and spray painting the word "retard" on classrooms.

The senseless attack at Goldfields School in Paeroa, northern Waikato, was discovered by a pupil's mother on Monday.

The green paint was daubed on classrooms, windows and the carpark.

"It just leaves you feeling sick," said Gary Quarless, principal of the school, which provides special needs education for about 60 pupils.


"What's really sad is that they've tagged 'retard' right across the window.

"That's just malicious and makes you wonder what is going through their heads."

Cars, fences, and half-built houses in the area have also been tagged with the same paint.

Local police are now investigating.

Mr Quarless was thankful that at least it happened during the school holidays.

"Some of our older pupils can read and have a level of comprehension and they would have been dreadfully upset to see it. They would have taken it very personally."

One of the school's pupils, James Vedder, died just before Christmas.

The vandalism attack would cost money for repairs and was another blow for the school, which is also trying to fundraise at least $250,000 to upgrade its facilities, Mr Quarless said.

He suspected it was local able-bodied kids "able to make conscious decisions" who were behind the vandalism.

"I just can't understand why someone would do that -- it's just beyond me," said Mr Quarless.

"You can understand young kids being angry, saying 'F*** school', to a certain extent, but it makes you feel empty when you see that."

Find out more about Goldfields School's appeal here.