GAINESVILLE, Ga, >> A liquid nitrogen leak at a northeast Georgia poultry plant killed six people Thursday and sent 11 others to the hospital, officials said.

At least three of those injured at the Foundation Food Group plant in Gainesville were reported in critical condition.

Poultry plants rely on refrigeration systems that can include liquid nitrogen. Sheriff’s deputies, the U.S. Occupational Safety and Health Administration and the state fire marshal were investigating the deaths and cause of the leak.

“It will be a lengthy process,” Hall County Sheriff Gerald Couch said. “It’s not something that’s quick.”

Foundation Food Group Vice President for Human Resources Nicholas Ancrum called the leak a tragic accident and said early indications are that a nitrogen line ruptured in the facility.

When leaked into the air, liquid nitrogen vaporizes into an odorless gas that’s capable of displacing oxygen. That means leaks in enclosed spaces can become deadly by pushing away breathable air, according to the U.S. Chemical Safety Board.

Gainesville is the hub of Georgia’s poultry industry, which is the largest in the country. Thousands of employees work across multiple processing plants around the city and much of the workforce, like in many meat processing plants nationwide, is Latino.

Workers who had fled the plant were gathered outside when firefighters responded to the leak Thursday morning, Hall County Fire Department Division Chief Zach Brackett said.

“Once the units arrived, they found a large contingent of employees that had evacuated, along with multiple victims that were in that crowd that were also experiencing medical emergencies around the facility,” Brackett said.

Beth Downs, a spokesperson for Northeast Georgia Health System, said five people died at the plant and one person died in the emergency room.

Hall County Sheriff’s Office spokesperson Derreck Booth said officials were trying to notify family members of the deceased. No names were released. Ancrum said maintenance personnel, supervisors and managers were among the victims.

“Every team member is equally important to us, and our hearts go out to their families and communities who have suffered such a devastating loss,” Ancrum said.

The plant was known as Prime Pak Foods until January, when it became part of Foundation Food Group, a privately held company that Ancrum said has four Gainesville-area locations. The plant takes raw chicken and processes it into products like chicken fingers and individual chicken cuts for restaurants and food service operations, partially cooking them and then freezing them for later use.

Previous safety violations at the plant show no problems with the refrigeration system. The plant has been cited by OSHA for violations four times in the past 10 years, online records show. The most serious of those was in September 2015, when 28 violations were initially cited, including citations for failing to make sure machines were properly safeguarded when being maintained to prevent injuries. Two other citations in 2017 involved employees who had fingers amputated by machinery.

Four in every 100 meat processing workers suffered a recordable workplace injury in 2019, according to the most recent federal statistics. That number has been trending downward. A total of 12 food processing workers died in the workplace nationwide in 2019.

Fourteen American workers died from asphyxiation linked to nitrogen in 12 workplace accidents recorded between 2012 and 2020, according to OSHA.

Eleven people injured in the Gainesville leak were treated for respiratory symptoms at the hospital, including three who were in critical condition, health system spokesperson Sean Couch said. He said five were in fair condition and three were treated and released.

At least four firefighters were injured and taken to the hospital with what Brackett described as respiratory complaints. One firefighter remained hospitalized late Thursday.

“He’s doing well and he should be going home tomorrow,” Brackett said.

Brackett said the remainder of the plant’s 130 workers were taken by bus to a nearby church where hospital workers examined them for injuries.

Students were kept safe inside a nearby elementary school during the emergency, though the leak was contained and not airborne, Hall County school officials said. The shelter in place order was lifted Thursday afternoon.