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.