Concerns for those downwind of huge Auckland fire

There is growing concern for residents downwind of a scrap metal fire in Auckland on Thursday morning.

The blaze has been burning for more than 24 hours now, with nine crews battling the blaze overnight in Favona.

Emergency services were called to Sims Pacific Metals on James Fletcher Dr in Favona, Mangere, just before 2am on Wednesday morning.

Eighty firefighters tended to the fire armed with 3km of hose. Those first on the scene said it would take them "a wee while" to get the blaze under control.

"The scrap metal pile's about 2000 tonnes of scrap metal. That includes vehicles, fridges, roofing iron, all sorts of scrap steel and materials in that pile."

The cars had been drained of fuel but there were still explosions as water failed to penetrate the thick pile of metal.

The blaze at its peak was just smaller than Eden Park, and is taking a "huge demand" on the fire service's resources across Auckland.

People are being reminded to keep clear of the smoke, shut up doors and windows and stay inside.