At least six people were killed and 12 hospitalized on Thursday after a suspected liquid nitrogen leak at a poultry plant in the U.S. state of Georgia, police and fire services officials said.

Five people died at the Foundation Food Group plant in Gainesville, about 60 miles (97 km) northeast of Atlanta, and one died after being transferred to hospital, the officials said.

Nicholas Ancrum, a spokesman for Foundation Food Group, said it appeared a nitrogen line had burst and the cause was under investigation.

“All these folks who came to work today didn’t expect something like this, so please keep them in your prayers,” County Sheriff Gerald Couch said.

All the bodies had been removed from the plant and authorities were working on identifying them and notifying the families, Couch said.

Of the 12 people injured, three were in critical condition, five were listed in fair condition and the remaining three had been released from hospital, officials said.

Nitrogen, typically an inert gas that becomes a liquid when supercooled, is widely used in frozen food processing plants. However, liquid nitrogen gas released in a confined space can rapidly displace oxygen in the air and lungs, according to the University of Delaware, leading to unconsciousness and lethal asphyxiation.

Last month, two workers at a Golden West Food Group plant in Los Angeles County, lost consciousness and died following an apparent liquid nitrogen leak there, according to the Los Angeles County Fire Department.

Four fire-fighters were injured in Thursday’s suspected leak, suffering respiratory ailments, while around 130 other people were evacuated to a nearby church, officials said.

The Foundation Food Group plant processes raw chicken into products like frozen chicken tenders and individual chicken cuts for restaurants and food service operations. It was known as Prime Pak Foods until the start of the year, when its name was changed under a merger between the two companies.

Georgia Governor Brian Kemp said on Twitter that he and his family are heartbroken over the news, and asked for all Georgians to pray for the families of the victims.

“May God be a hand of peace, comfort, and healing in the days ahead,” he wrote.