The leak happened at the newpage paper mill.
Officials say a worker accidentally combined two chemicals, causing chlorine gas to escape into the air.
Those exposed to the gas were taken to a special tent at the hospital for decontamination, then given oxygen for respiratory problems.
A number of people were also evacuated from that section of the building as a precaution.
All of the workers who were exposed to the chemical are expected to fully recover
The fire chief says the gas was confined to one building at the mill, and never posed a threat to the town or the environment.
OSHA is now investigating the incident.