Poison had been inserted in the drill holes.
"The children just couldn't comprehend what had happened and why someone would want to do that," Mr McLeod said.
A couple of the large native trees, which are up to 60 years old, show signs that leaves have died in some sections.
Other sections of the same trees, however, still have healthy leaves. One tree has shown no signs of deterioration, although a neighbouring one is bare of green leaves, except for a couple of spring outbreaks.
"It's a case of fingers crossed at this stage - we just hope they can recover but the experts will be able to tell us that."
If the worst came to the worst, there were already plans in place to replace them.
"Oh yes, we will do that - we are a sun-smart school and the trees are important because the younger ones, the mainly 5 to 7-year-olds, love playing out there under them."
A group of parents were already preparing a fund-raising website in case work was required and new trees sought.
Mr McLeod said if the trees were not going to fully recover they would be removed, with safety the top issue.
Someone had entered the school grounds through a gate off Colenso Ave, which had a faulty lock. It had since been replaced.
There had been suggestions someone in the neighbourhood was unhappy with the shade the trees e cast, although Mr McLeod said there had been no complaints.
Police were advised and letters delivered to residents in the area pointing out the penalties for such vandalism.
No one had been identified as the culprit. Mr McLeod said nearby residents he had spoken to were disgusted to hear what had happened.
