Scores of firefighters have extinguished a large fire at a steel factory in Otahuhu.
Police passing by noticed the blaze at Pacific Steel's manufacturing plant in Otahuhu at around midnight and called the fire service.
Parts of the building on James Fletcher Drive were "well involved" with the blaze covering two storeys, the fire service said.
When firefighters got into the building they found fire in a conveyor belt leading into a car shredder unit.
It's caused damage to one building, but not the rest of the complex and crews were clear of the scene by around 4am.
Northern fire communications shift manager Megan Ruru said last night 14 fire trucks were at the scene where a shredder control had caught fire causing a 10 metre by 10 metre blaze.
It is not believed that anyone was inside the building.
According to their website Pacific Steel is New Zealand's only manufacturer of wire rod, reinforcing bar and coil products with a production rate of around 250,000 tonnes per year of manufactured steel.
The company has been manufacturing reinforcing steel products for over 50 years.