The lightning bolt struck a rugby goalpost before travelling along the ground and connecting with the fence of the school's tennis court before hitting the classroom and striking the four teachers.
Kane said they were shaken, but back up and running today.
Internet access and fire safety indicators fried during the lightning were still being repaired.
This morning Auckland felt the brunt of a dramatic lightning storm that caused flights to be cancelled and delayed and houses to shake.
A woman at Happy Campers in Mangere collapsed and was hospitalised after a lightning strike.
About 2000 lightning strikes in Auckland this morning, according to MetService.
The bad weather is expected to move down to the South Island from this afternoon and into tomorrow.
A severe thunderstorm watch has been issued for Buller, Westland and Fiordland, and another is in place for Clutha and Southland.