Large shed fire full of hay bales 'well involved' south of Hamilton

Firefighters have activated a third alarm to help fight a "well involved" shed fire in the Rukuhia District south of Hamilton.

The shed, 100m by 100m, is a complex of industrial businesses which houses cars, machinery, hay and pool manufacturing equipment.

Fire Emergency New Zealand Waikato area commander Roy Breeze said about "70 per cent of the building is totally damaged by fire".

"We are now stopping the fire from coming into the areas that are not burned," Breeze said.

At its peak five water tankers, a dozen other appliances and up to 50 firefighters were on scene.

"We have a maize paddock beside us and we are monitoring it too."

A skeleton staff would remain on site until around midday.

Lines of cars have queued up on Raynes Rd to watch the blaze. PHoto / Belinda Feek

Massive flames could be seen from the shed which is surrounded by a maize paddock.

The shed is not hear any other residential or commercial properties.

Explosions could be heard coming from the burning building.

The fire is just a few hundred metres from Hamilton Airport

Earlier lines of cars queued up on Raynes Rd to watch the blaze and some people were standing on their cars to get a better look.

Hamilton Airport fire and rescue personnel said the fire was not affecting any flights in or out of the airport.