A huge fire just north of Christchurch was started by fireworks, police have confirmed.
Firefighters are continuing to battle a 133-hectare vegetation fire in Pegasus which started on Wednesday night and forced more than 100 people to evacuate.
Fire and Emergency New Zealand (FENZ) were called to the scrub fire just before 8pm on Wednesday.
FENZ said 12 trucks and 70 firefighters have been battling the blaze which was travelling "fast" toward Woodend Beach at one stage.
Helicopters and fixed-wing aircraft are dropping thousands of litres of water on the fire.
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."
Insp Cooper said police encourage anyone intending to light fireworks this season to ensure they do so safely. This includes not lighting them in windy or dry conditions, or around anything that might catch fire, such as dry grass or leaves.
Fireworks can only be sold between November 2 and 5 to adults over 18.
"Police would like to thank those evacuated last night for their compliance and patience," he added.
All 130 residents of Woodend Beach Holiday Park were evacuated as a precaution and FENZ was also forced to evacuate horses from a nearby equestrian centre.
Incident controller Dave Berry said evacuated residents will be allowed to return home this evening from 5pm through a managed re-occupation. But Berry warned residents should be prepared to evacuate again if needed.
"Crews will be controlling and monitoring the fire throughout the night. If anyone has any concerns, please call 111."
Health warnings
Te Whatu Ora Health New Zealand has warned people living near the fire the smoke could cause moderate health risks.
Air in the area is smoky and anyone who is sensitive to smoke - such as people with heart or lung conditions, pregnant women, young children and the elderly - may experience symptoms like coughing, shortness of breath or eye, nose and throat irritation.
Waitaha Canterbury's medical officer of health Dr Ramon Pink said exposure to smoke can worsen pre-existing health conditions such as asthma and heart disease.
"People affected by the smoke should close windows and doors, stay inside if it's safe to do so and avoid or reduce outdoor exercise," Dr Pink said.
"Anyone experiencing health issues from the Woodend fire should phone their usual general practice team in the first instance.
"For families returning to homes or holiday accommodation after the fire, it is important to know the smell of smoke in your properties presents no serious threat to health."
Health NZ urges people to keep their windows and doors shut, switch their air conditioning to 'recirculate', air out their house when the smoke clears, and keep pets and their bedding inside with clean water and food.
Strong winds cause issues for firefighters
The winds have started to die down on Thursday morning, making fighting conditions slightly better but Incident Controller Colin Russell said they're meant to pick back up later today, which will cause firefighters issues tackling the blaze.
MetService has issued a strong wind watch for the Canterbury Plains from 9am until 3pm Thursday.
"At the moment, as you can see, the wind is relatively light. So we've got this window to actually make some impact on that," Russell said at a press conference on Thursday.
"The forecast is for the wind to pick up today. So we're up against it once that wind hits the forecast, winds of 50 kilometres an hour, it'll start causing us some problems and flaring up hot spots in the forest."
Russell said "it's too early to say how the fire started" but added they have appointed a fire investigation team.
"It's very hard for the fire crews to get in there safely and get water on the fire and in the sand dunes," Russell said.
"Underfoot is very soft and dangerous and evacuating in a safe manner if anything goes wrong is also problematic, so we take great care as to where we put our people so they don't get in danger."
Helicopters have carried out aerial surveillance of the large fire which covers approximately 5km, Russell said.
"The operation will continue today with another seven fire crews supported by tankers and five helicopters flying up to get into the guts of the fire and make some impact on the fire today," Russell said.
All 130 residents of Woodend Beach Holiday Park were evacuated as a precaution and Civil Defence has established a welfare hub at the Woodend Community Centre.
"A second community meeting will be held for evacuees and residents in the vicinity of the fire at 10am in the Woodend Community Centre, which has also been set up as a welfare hub by Civil Defence," Russell said.
FENZ was also forced to evacuate horses from a nearby equestrian centre, but this was completed without any incident.
Russell said they aim to get residents back into their homes "as soon as we can" but they need to assess the damage first.
"Firefighters have also been carrying out structure protection at the camping ground and tackling spot fires," Russell said in an earlier statement.
"Heavy machinery had been used to create a firebreak on Pipeline Road, which runs off Ferry Road and the Pines Beach end."
Russell said to the best of his knowledge, no homes or property have been lost, although helicopters will be up at first light to give a better assessment.
Waimakariri District Mayor Dan Gordon said it has been a real team effort to tackle the continuing blaze.
"It's been a real community effort led by FENZ and I'm standing here beside Colin and his team this morning to say thank you for all that they've done for our community overnight and will continue to do so. We're incredibly grateful," Gordon said at the press conference.
