Police and Fire and Emergency NZ (FENZ) have closed public access to Te Mata Peak in Havelock North as they battle a large scrub fire.
Emergency services were called to the popular scenic spot after 8:30pm on Friday when the blaze broke out.
The access road, Te Mata Peak Rd, has been closed and FENZ is now considering closing Waimarama Rd. The public is urged to avoid the area.
A witness told the NZ Herald he heard fireworks being set off just before the fire broke out.
"I was going to call the police line 105 because all I could think was 'what idiots' and then I saw the flames."
Police and FENZ will be investigating reports the fire was started by fireworks.
It comes after a huge fire at Canterbury's Pegasus Beach - just north of Christchurch - was started by fireworks.
The 133-hectare vegetation fire started on Wednesday night and forced more than 100 people to evacuate.
In an update on Thursday afternoon, Canterbury rural area commander Inspector Peter Cooper confirmed police have spoken to two young people in relation to the incident. One of them has been referred to Youth Aid.
"We are pleased to have been able to quickly identify those allegedly involved and we hope this brings some reassurance to the community," he said in a statement.
"It has been established the fire caught following a firework being let off."
