A fire that halted production at Fonterra's Kauri site in Northland started in a powder evaporation building.
As a result of the fire one person was taken to hospital and four others checked by St John ambulance staff.
The alarm was raised about 7.30pm on Thursday and Fire and Emergency staff, police and St John ambulance staff were called to the site 12km north of Whangārei, on State Highway 1.
Fonterra spokeswoman Louise Kattera said the staff member was taken to hospital for some extra precautionary tests and they had been discharged by thismorning.
Four other staff members were checked on site by St John ambulance officers and did not need to be taken to hospital.