According to the spokeswoman, five people were killed at the scene, while another died in the emergency room.
At least five firefighters were injured and taken to local hospital, while some 130 employees were transported to a nearby church, where they were examined by medical personnel. Some of the staff members were taken to hospital.
Several facilities in the vicinity of the plant have been closed, including a nearby elementary school. According to Hall County officials, the leak has been contained.
The cause of the leak is yet to be identified.