The blast occurred overnight yesterday in the city of Cordoba, Argentina's second most populous city, some 700 kilometres north of Buenos Aires.
Officials said the injured were neighbours of the plant, which was closed at the time of the explosion.
"I was laying in bed asleep, when I heard a tremendous blast. I thought a plane had crashed in front of my house," Claudio Utrera, a resident of the neighbourhood, told the daily La Voz del Interior newspaper.
