A federal investigative board believes a deadly nitrogen leak at a Gainesville poultry processing plant was related to a conveyor belt problem.

Six workers were killed at the Foundation Food Group on Jan. 28. The plant uses nitrogen to flash-freeze chicken, and an “inadvertent release” happened on one of the plant’s production lines. About a dozen people were injured and taken to a hospital, and 130 people were evacuated.

The conveyor belt ferried chicken to workers on one of the production lines the facility runs, according to initial findings by the U.S. Chemical Safety and Hazard Investigation Board.

The line where the leak happened was out of service due to the belt. The production line featured an immersion bath used to flash-freeze chicken with nitrogen, the board said. The board previously said the leak was related to “unscheduled maintenance.”

Killed in the incident were Jose DeJesus Elias-Cabrera, 45, of Gainesville; Corey Alan Murphy, 35, of Clermont; Nelly Perez-Rafael, 28, of Gainesville; Saulo Suarez-Bernal, 41, of Dawsonville; Victor Vellez, 38, of Gainesville; and Edgar Vera-Garcia, 28, of Gainesville.

“I talked to all these people daily,” plant employee Yamilex Estrda said. “They were always there for me.”

The Atlanta Journal-Constitution spent time with grieving relatives and community members to tell the stories of the six people killed in the plant disaster. The resulting story has been retweeted more than 2,000 times.

GoFundMe campaigns set up to assist with funerals and other expenses had raised $76,000 by Monday afternoon.

The Chemical Safety Board’s work is ongoing, and the board’s chairman and CEO Katherine Lemos said at a Jan. 30 news conference in Gainesville that a full report could take several years. The board makes safety recommendations but does not issue citations or fines.

The incident is also under investigation by various other federal, state and local agencies.