He said fireworks were misfired into a crowd of families.
Sutherland was giving people first aid and spoke to girl called Britney, about 10-years-old, received burns to her leg after protecting a baby from the misfiring fireworks.
He said she was very upset and sore but has described her as a hero.
Sutherland said many people she was with were also injured.
City Church has apologised and says it's investigating what went wrong.
The church said in a post on its Facebook page that "something went wrong with the fireworks" during what was supposed to be a family-friendly fireworks display.
"In the interest of public safety the event was immediately stopped and we are investigating what went wrong," the post said.
"We apologies to everyone, especially those who were hurt."
A Worksafe spokeswoman said an inspector has started making initial inquiries.