The principal of a Hamilton school that was struck by lightning, injuring four people, said the blast did fry some electrical equipment in the classroom nearest the strike.
The lightning appeared to hit some rugby posts at Hamilton North School before travelling through the ground and hitting a school building.
Waikato Police Senior Sergeant Tracy Shaw said witnesses saw a blue streak around 2pm when the lightning strike happened at the school.
"There was one report that they saw a blue streak going through the sky at about the time the lightning struck.
"There were burn marks through the rugby field and it appears that lightning struck some posts and that has gone through to the school building."
Four people in the building believed to be classroom suffered moderate injuries and were taken to Waikato Hospital.
School principal Tony Kane said there was huge flash and bang all at once which set off the smoke detectors.
He said the lightning did fry some electrical gear in the classroom nearest the strike.
Mr Kane said the four staff who were taken to hospital were not hit by lightning.
"Coming through the rooms they have a bit of tingling, that's the main thing just from I suppose could be shock from the blast being so close, it's hard to know, but no one was electrically upset."
Mr Kane said no children suffered injuries.
"Children have been checked out and they seemed fine and we will keep an eye on them again tomorrow to see how they ae and hopefully the staff are fine too."
Mr Kane said schools plan for most events but a lightning strike so close came as a real surprise.
"I was in the main office actually and I can tell you I thought it was really, really close, that loud and the bang and flash all at once was quite frightening."
Tony Kane said it will be school as usual tomorrow and the kids may have some stories to tell.
One Hamilton local, Roda, said the thunder was so strong, she thought a bomb had gone off.
"Literally the whole house shook- like my bed really shook and my sister was in the lounge and she said [the lightning] was the brightest flash she's ever seen," said Roda.
"We were just panicking about it. It was terrifying."
The four people taken to hospital have since been discharged.