A video shows that the fireworks at the Waikaraka Speedway event landed in the crowd.
Event promoter Bruce Robertson said a woman was struck on the arm.
It was a successful event with a crowd of about 6500 and many others parked on the streets to watch, he said.
Ban the Boom New Zealand spokesperson Alice Hayward said people should only be allowed to light fireworks on Guy Fawkes night.
People should be aware that fireworks could cause fires, damage properties and injuries, she said.
Hayward also hoped everyone would be safe tonight.
ACC data shows children under 10 make up one-quarter of all fireworks-related claims each year.
In the four years to 2022, the Accident Compensation Corporation accepted 1376 fireworks-related injury claims, at a cost of almost $3 million, of which 329 were for children under 10.
ACC spokesperson James Whitaker said the injuries included burnt hands, fingers and eyes.
Such injuries could be avoided if people were more mindful, he said.
https://www.odt.co.nz/star-news/star-national/call-caution-after-fireworks-burn-womans-arm Call for caution after fireworks burn woman’s arm