POLAND — Fire departments from several towns responded to an ammonia leak Thursday morning at the Poland Spring Water Co. bottling plant. The building was evacuated and four people were sent to area hospitals to be examined, officials said. 

A  spokesman for Central Maine Medical Center in Lewiston said four patients were brought in for examination as a result of the leak. Each was later released from the hospital.

Fire crews from several area towns were joined at the scene by officials from C.O.B.R.A., a hazardous materials team made up of officials from various police and emergency agencies across the county. 

“We had a lot of help out there,” Poland fire Chief Mark Bosse said. “I’m really thankful for all the working relationships we have with all these county communities.”

Bosse said the ammonia leaked from equipment that’s used in the cleaning process. By late Wednesday afternoon, repairs had been completed and the plant was fully operational again.

“All is good,” Bosse said. “They’re back up and running.”

Ammonia is a colorless gas that can be fatal if inhaled and corrosive if it comes in contact with skin or eyes. The severity — and what medical care is needed — can depend both on the concentration of the gas and the prior health of the person exposed.