A fire at Auckland's Sanitarium factory appears to have started in an oven.
The fire service were called to the Pah Rd, Royal Oak, factory about 9am.
"We received a number of calls about smoke coming from the factory," Onehunga Senior Station Officer Chris Power said.
"The fire looks like it started in an oven and spread through the ducts up to the extractor fans."
Six crews attended and a fire investigator had visited the site.
Fire crews were able to get the blaze under control fairly quickly, Power said.
All factory staff were evacuated safely and no-one was injured.
"We're now at the stage of assessing the damage, we don't have a lot of detail at this stage," Sanitarium national category manager Mark Roper said.
"How long it is until we're back to normal operations we don't know yet."