The Singapore Civil Defence Force posted on its Facebook page that an ammonia leak occurred at 1 Fishery Port Road on Friday.
It notes that it was alerted to the incident at about 11.40am.
It is said that the leak in a first floor chiller room was shut off by the company and its staff were evacuated prior to SCDF's arrival.
SCDF decontaminated 3 people by washing them down with water. They were conveyed to Ng Teng Fong General Hospital in a conscious and stable condition.
SCDF resources are still at the scene.
Ammonia is widely used as a refrigerant gas, a colourless gas with a sharp, penetrating, intensely irritating odour and a colourless liquid under pressure, it is not considered a flammable gas. However, a large and intense energy source may cause ignition and/or explosion.
Ammonia gas is a corrosive gas and may be fatal if inhaled. Ammonia gas may cause lung injury, and the liquefied gas can cause frostbite and corrosive injury to eyes and skin.