A man has been seriously injured in an explosion at the Affco Moerewa Meat Processing Plant in the Far North.
A Fire and Emergency services spokesman said there had been an explosion and fire in a coal hopper.
Two appliances were sent to the scene.
As of 9.30pm the fire had been put out, and crews were working to cool down a boiler.
St John said ambulance services were called to the event at 7.28pm and treated one person in a serious condition, with burns.
A rescue helicopter was sent to transfer the ijured person to Middlemore Hospital in Auckland.
A spokesman for the Auckland Westpac Rescue Helicopter said they were tasked to Bay of Islands Hospital, in Kawakawa, to assist with the urgent transportation of a male patient in his 30s suffering extensive burns to his body.
A reporter at the scene this morning said there were no visible signs of smoke or fire damage from the road in front of the plant.
Two Fire and Emergency vehicles were parked outside buildings on the freezing works site off to the right of the main entrance.
Two people in hi-vis safety vests were seen entering a nearby building.