A fire at a Sanitarium cereal factory in Auckland on Wednesday broke through the multi-storey building's roof and sent flames and thick black smoke into the air.
Passers-by alerted the fire servce which had already registered an automatic alarm at the Pah Road site just before 9am.
The fire service say the blaze, which is now out, started in an oven and spread up through the roof.
A Sanitarium spokesperson Mark Roper says the factory is now being assessed for damage but it's too early to say if cereal production will be affected as a result of the fire.
The building was evacuated and no-one was hurt.
