Firefighters battling a huge blaze in South Auckland today have now contained the fire to the building.
A Fire and Emergency NZ spokesman said a building and cars caught fire on Jellicoe St, in Manurewa.
The section where the fire broke out had reportedly served as a junk yard.
An emergency call was received at 11.30am, and more than 20 fire trucks were battling the blaze.
"There are multiple appliances in use and they are attacking it from the exterior at this stage," the spokesman said.
"We have fire investigators there, but until the fire is out they won't know what the cause is for some time."
It is believed no one was injured.
Mohamoed Juanmiry told Stuff the fire had broken out at his family's business.
He received a call about the fire and rushed to the scene, he said.
No one had been at work on Wednesday, he said.
Witnesses reported a large initial boom and a lot of additional noises following that. There were also flames very high in the air, and a considerable amount of smoke.
Jeff Ottaway from DDS Contracting, which is next door to the fire, said there were plumes of smoke everywhere.
He said the site is a car wreckers, where they "chop up cars and sell the parts" - so there were a lot of tyres and car parts.
"When that smoke was going up it was pretty intimidating," he said.
Ottaway said Fire and Emergency had told him it would be six hours before they could return to work.
Police said they were assisting FENZ with traffic management and that Jutland Rd in Manurewa had been closed.
The blaze had also forced train delays and cancellations on the Southern rail line.
Ryan Marshall of Pearce Brothers Manurewa said it is the biggest fire he has seen.
"It looks like a car removal company, with lots of tyres and stuff like that burning.
"I can see it from my window and it looks like they have just put it out now, because the smoke is changing colour," he said.
"When I was about 400m away from the fire, you could hear all the cracking and popping and bits exploding.
"There were little bits coming out, I don't know if it was glass or shards coming out."
Marshall said the whole area had come to a gridlock.
"All the traffic in the whole area has come to a standstill," he said.
"The smoke is still there, but it definitely looks like they have got it under control because I can see the smoke has stopped."
Ramona Talaepa from Little Bears Educare said they had to evacuate 20 children from the building due to the fire.
"They were all panicking and crying and we had to calm them down and tell them that everything is going to be fine and they will be ok," she said.
"One of the police officers, who was very kind, helped us evacuate the building.
"He told us to come further down to Ruth St and helped us walk the kids and comfort them."
Talaepa said the older children were frightened because they saw the smoke.
"One of the centre managers called the parents to come and pick up their children, while other staff did the evacuation," she said.
"A lot of them were worried, but we told them their children are safe with us."
Talaepa said they were happy when they were told it was safe to return as children were "starving and busting to go to the toilet".
Summer Mills-Metcalf took her own life in 2018 while taking fluoxetine.