"The real sad thing was the number and ages of these kids around watching and participating."
He said it was quite late at night and the gathering involved children as young as 6 and 7, up to teenagers and adults.
No information was available on the seriousness of the child's injuries.
There was damage to a building, litter was left lying around the town and a dead bird was found at the base of the large tree that had caught fire.
Morunga said it was the first time there had been significant issues at Guy Fawkes in the time he had been with Tūrangi Police.
They will be working with the Taupō District Council and shopkeepers that sell fireworks and are keen to hear from other people in the town about how Guy Fawkes should be managed in the future.