CONYERS, Ga. (TND) — Residents near Atlanta were asked again to shelter in place Tuesday if a chemical cloud moved over their neighborhood as plumes from a chemical plant fire continued to shift overnight.

A shelter-in-place order had just been lifted Monday for more than 90,000 residents after a fire sent a massive plume of dark smoke into the sky Sunday.

Air quality surveys done by the Environmental Protection Agency and the state Environmental Protection Division "revealed the harmful irritant chlorine" was detected in the air from the fire at the BioLab plant.

"We are aware and are assessing the situation. The plume has consistently shifted throughout the night," Rockland County officials wrote on social media. "We ask that you shelter in place if the plume moves over your vicinity or if there is a strong odor of chlorine. If you have respiratory issues, we encourage you to shelter in place. We will provide an update as quickly as possible."

The fire was under control by 4 p.m. Sunday, according to officials.

Multiple media outlets reported the fire started when a sprinkler malfunctioned at the plant around 5 a.m. causing a chemical reaction and a large, hazardous plume, along with a small fire on the BioLab roof.

Authorities added the small fire on the plant's roof was initially contained but reignited Sunday afternoon.

There were employees inside the plant, but no injuries were reported.

The U.S. Chemical Safety and Hazard Investigation Board(CSB) said in a statement Monday that they are sending investigators to look into the major chemical fire that caused as many as 17,000 people in the area to evacuate.

"We are sending investigators to the site to determine the cause of this dangerous incident and the safety gaps at the facility that allowed this huge fire to occur," Chairperson Steve Owens said. "Tens of thousands of people have been put potentially at risk by this catastrophe."

This is the second time the CSB has investigated the lab in Conyers.

"In September 2020, the CSB investigated a chemical reaction and decomposition at the facility which released a plume of hazardous chemicals, including chlorine, that exposed Bio-Lab personnel and nine firefighters to dangerous fumes," CSB explained. "Surrounding businesses in the area were evacuated, and a portion of Interstate 20 near the facility was closed for six hours."

BioLab's website says it is the swimming pool and spa water care division of Lawrenceville, Georgia-based KIK Consumer Products.

CSB added the chemicals used by BioLab containtrichloroisocyanuric acid (TCCA) that can undergo a chemical reaction that generates heat when it comes into contact with small amounts of water and does not dissolve.