A major ammonia leak at the AFFCO meat works in Moerewa in the Far North has now been isolated and authorities have been confirmed that no one was injured in the spill.
Emergency services were called to the processing plant on State Highway 1 at 6.30pm.
Northern Fire Service communications shift manager Megan Ruru said there were initial concerns that some people were unaccounted for however all those inside the building have since been safely evacuated and the leak has been contained by fire crews.
Ruru said there were six fire crews at the scene and an emergency decontamination was being carried out.
A St John's spokesperson said two ambulances were sent to the scene but had since left as no one required treatment.
AFFCO's general manager Andy Leonard said emergency services were checking to see whether it was safe for workers to go back into the building about 8pm.
The cause of the leak was not yet clear, Leonard said, but it started in the plant's refrigeration unit.
"Ammonia leaks in refrigeration plants aren't uncommon."
The company would investigate the cause of the leak as soon as possible, he said.
All 60 night shift staff who were working at the time had got out safely and were all okay.
"The consequences are not major at this stage", Leonard said.
Once emergency services had confirmed it was safe for staff to go back into the building it would be business as usual.
Ammonia is a colourless gas with a with a characteristic pungent odour.
It can irritate the skin, eyes, nose, throat, and lungs.
According to AFFCO's website, the processing plant is "an integral part of the Moerewa community within which it operates, and being the largest regional employer, enjoys good support from farmer suppliers."
AFFCO Moerewa processes ovine and bovine species, including calves.
"It has its own on site blast freezing and cold storage operation, and operates a rendering plant which produces quality meat and bone meal, and tallow," the website says.