Firefighters have isolated an ammonia leak in a Hamilton meat factory which has shut down the North Island main trunk line and drawn more than 40 firefighters, police and St John Ambulance to the scene.
The leak at the Goodman Fielder meat factory in the industrial suburb of Frankton was discovered after 10am and 10 fire appliances are involved in the mass response.
Fire Service Waikato area commander Roy Breeze said the risk of an explosion was low and the need for evacuation was not necessary yet.
"We've just found it. The guys have isolated it now and it's just a matter of trying to work out how to ventilate the gas that's in the system."
Hazmat firefighters in level four suits had entered the large building, where stuffed cheeses and meat were being stored, to investigate.