Some residents east of Atlanta were evacuated while others were told to shelter in place Sunday to avoid contaminants from a chemical plant fire that sent dark, billowing gray smoke into the air.

Interstate 20 was shut down in both directions in the area, the Georgia Department of Transportation said in a post on X.

The fire ignited when a sprinkler head malfunctioned around 5 a.m. Sunday at the BioLab plant in Conyers, Rockdale County Fire Chief Marian McDaniel told reporters. The malfunction caused water to mix with a water-reactive chemical, producing a plume of chemicals. McDaniel said she wasn't sure what chemicals may have been contained in the plume.

BioLab's website says it is the swimming pool and spa water care division of Lawrenceville, Georgia-based KIK Consumer Products. An automated message at the phone number on the parent company's website said to call back during business hours.

"We are actively responding to an occurrence at our facility in Conyers, Georgia," a BioLab representative said in a statement provided to The Atlanta Journal-Constitution. "Our employees are accounted for with no injuries reported. Our team is on the scene, working with first responders and local authorities to assess and contain the situation."

A small fire on the plant's roof was initially contained, but reignited Sunday afternoon, Sheriff Eric Levett said in a video posted on Facebook as gray smoke spewed into the sky behind him. He said authorities were trying to get the fire under control and urged people to stay away from the area.

People in the northern part of Rockdale County, north of Interstate 20, were ordered to evacuate and others were told to shelter in place with windows and doors closed. Sheriff's office spokesperson Christine Nesbitt did not know the number of people evacuated.

The federal Environmental Protection Agency and the Georgia Environmental Protection Division were both on site, county Emergency Management Director Sharon Webb said. The agencies are monitoring the air "to give us more of an idea of what the plume consists of."

McDaniel said crews were working on removing the chemical from the building, away from the water source. Once the product is contained, the situation will be assessed and officials will let residents know whether it is safe to return to their homes, she said.