CONYERS, Ga. — 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 a massive plume of dark smoke high into the sky that could be seen from miles away.

Interstate 20 was shut down in both directions in the area, the Georgia Department of Transportation said in a post on X. Reports said traffic was snarled as vehicles backed up in the area after the closure.

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 there were employees inside the plant but no injuries have been reported at this time, The Atlanta Journal-Constitution reported.

The newspaper said the billowing cloud of smoke was visible Sunday afternoon as far as 30 miles (50 kilometers) away at Atlanta’s international airport south of the city. It added no injuries were immediately reported.

“Once we can get that chemical out of the building and allow it to burn off we’ll be in a much better shape,” McDaniel said.

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 although it covered a large portion of the community of Conyers.

Sunday evening the Newton County School District announced that classes would be canceled on Monday. “Out of an abundance of caution for the safety, health, and well being of all students and staff, we have determined that the best course of action is to close all schools tomorrow…,” it said in a statement.

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.