Firefighters from as far away as Whangarei battled to put out a serious blaze at the Affco freezing works in Moerewa, which is the town's biggest employer.
The fire broke out in the administration building's electrics room at 7.55pm on Friday, just after a Christmas party for 600 staff and family members had wound down for the evening.
Two volunteer fire crews from Kawakawa and one each from the Paihia and Kaikohe brigades were called out, as well as a paid crew with an aerial appliance from Whangarei. St John Ambulance attended but was not required.
Kawakawa Fire Brigade station officer Alistair Leitch said the company had an evacuation plan and everyone was outside when firefighters arrived. No one was hurt and there were no concerns around the Christmas party, which was in a field on the far side of the freezing works.
Firefighters had to enter the building wearing breathing apparatus and had the blaze under control within half an hour. Damage was limited to the electrics room.
Affco electricians and site engineers were assessing the damage on Friday night to determine whether the plant could resume operating today.
Mr Leitch said the brigade had a plan for fighting fires at the freezing works, which was the biggest employer in Moerewa.
"Quite a few of our guys work here," he said.
"The firefighters did a great job, bringing it under control and saving 90 per cent of the building. Affco's a large employer in this area - any further damage could have caused major delays in getting the plant up and running again."
Mr Leitch put the limited damage down to the plant's fire detection system, which raised the alarm within seconds and automatically alerted the Fire Service, plus the volunteer firefighters' quick turnout and quick knock-down of the fire.
It was the Kawakawa brigade's biggest fire callout of recent times, he said.
The last firefighters left about 10pm.