A chemical fire at a Rockdale County business prompted authorities to evacuate residences and call out a hazmat team early Saturday.

About 4:30 a.m., a 911 caller reported smoke and a chemical smell coming from BioLab on Old Covington Highway, Rockdale police spokesman Michael Camp said.

Fire responders used foam to contain the runoff. “Minimal” flames were visible, Camp said.

Residences were evacuated one mile north of Old Covington Highway to West Avenue inside Conyers city limits.

A chemical reaction with some buckets of chlorine powder pellets on one pallet is believed have caused the fire, Camp said.

No injuries were reported, and the fire was completely out by 7 a.m.