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Firefighters have subdued a ferocious chemical fire in the Auckland suburb of Mangere overnight.
The fire, at a quarantine treatment factory, had fire fighters battling the toxic chemical laden blaze until the early hours of this morning.
Witnesses said they saw fireballs shooting into the air from the QTC factory's roof on Aintree Ave in Mangere.
The blaze was a fifth alarm fire - the worst type on a scale of one to five and happens only about every two years.
The factory fire exploded into life around 7pm, belching highly toxic chemical fumes and explosions into the air, forcing the evacuation of nearby workers.
Manukau City fire chief Larry Cocker said the fire was fuming and smouldering by 1am this morning.
"We will be wanting to hand the incident over to insurance assessors and contractors who will be cleaning up any hazardous waste left over," Mr Cocker said.
Two fire trucks have been at the site overnight, monitoring hot spots.
Mr Cocker said the cordon has been moved back and is only blocking the factory so businesses in the area can open as usual this morning.
He said fire fighters stayed upwind, outside and wore breathing apparatus and no one was injured.
"We kept the ambulances out of business," Mr Cocker said.
The factory is accredited by the Ministry of Agriculture and Forestry as a quarantine treatment centre.
It is thought to be involved in the chemical treatment of potentially contaminated items such as souvenirs and animal skins brought into the country through Auckland International Airport.
The fire gutted the factory, which held chemicals such as methyl bromide and cyanide.
People inside at the time of the fire managed to escape unscathed.
Those in surrounding buildings were evacuated and a cordon was set up around the factory.
Mr Cocker said because of the toxic fumes' danger firefighters had to fight the fire from outside the building.
He said liquefied petroleum gas cylinders and pressure cylinders in the factory might have caused the fireballs. "They all went with reasonably loud pops and that got everyone's attention."
The building was not fitted with sprinklers. "It has caused [the owner] a significant loss," Mr Cocker said.
Fire safety officer Ray Coleman said the fire appeared to have been caused by a "processing problem" at the factory and did not appear to be suspicious "at this stage".
Shane Corbett, who works in a nearby building said: "I saw a fire engine go past and then I was outside and saw smoke billowing."
He said he could see the paint starting to peel.
"There was just a really loud explosion which I felt [and] ... good toxic smoke coming off [the building]."
