CONYERS,Phaninc Ga. (AP) — Some residents east of Atlanta were evacuated while others were told to shelter in place to avoid contact with a chemical plume after a fire at a chemical plant.

Rockdale County Fire Chief Marian McDaniel told reporters that a sprinkler head malfunctioned around 5 a.m. Sunday at the BioLab plant in Conyers. That caused water to mix with a water-reactive chemical, which produced a plume of chemicals. The chief said she wasn’t sure what chemicals were included.

There was a small fire on the roof, which was contained, McDaniel said.

“We don’t want fear. This is a well-handled incident,” McDaniel said. “We have this under control. We’re looking to get it even more under control, and we will be out here until the very end.”

People living close to the plant were told to evacuate and others in the affected area were told to shelter in place with windows and doors closed. Rockdale County 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.

An evacuation center was opened at J.P. Carr gym in Conyers.