Chemical storage warehouse in South Auckland damaged by fire

The fire damaged roof of a chemical storage facility at Wiri. Photo/via Twitter

A fierce blaze at a giant chemical storage factory in South Auckland is under control and its hazardous contents no longer pose a danger.

Fire crews from all over the city were called to the Osmose NZ factory in Mayo Rd to contain a massive blaze that engulfed the three-storey building.

It took two hours to bring the fierce blaze under control. Firefighters waited for daylight to ventilate the badly damaged warehouse.

Firefighters were now damping down hotspots at the factory.

Cordons remain on Mayo Rd in the industrial suburb of Wiri and diversions are in place.

Quick work by fire crews is being credited for saving the plant from total ruin.

At its height 15 fire crews were at the scene.

Fire Service northern shift manager Megan Ruru said the fire broke out just before 4am.

The enormous 100sq m factory was used to house chemicals, Ruru said.

Decontamination units were set up at the site to treat firefighters.

She said the building was well ablaze when crews first arrived, but the fire was not threatening neighbouring buildings.

Fast action by firefighters has saved chemical storage company Osmose NZ from complete destruction. Photo/Twitter

The building's owner helped firefighters identify the chemicals stored in the building.

A fire spokesman said efforts were now turning to salvage.

All hazardous substances on the site had been contained.