The ambulance service says two people were taken to hospital following an ammonia leak at the Tip-Top ice-cream factory in the Auckland suburb of Otahuhu on Wednesday afternoon.
An ambulance spokesperson, Jarron Phillips, says the incident happened just after 4 o'clock. One person was being treated for inhalation problems, he says, while the other's eyes were irritated.
Mr Phillips says the area surrounding the spill was isolated but staff were evacuated as a precaution. Work later resumed, with a night-shift worker at the factory saying that everything was under control and the small leak had been quickly dealt with.