(CBS/WTAJ) — Officials in North Carolina say a fire at a zinc production plant in Mooresboro caused some residents to evacuate the area early Monday.

The American Zinc Products plant was still burning around 5 a.m. The fire started at the plant, located near the border between North and South Carolina on Sunday night.

Deputies went door-to-door, warning people to evacuate as the burning plant released sulfuric acid into the air, and the county says about a half-mile area has been evacuated.

The Rutherford County assistant Fire Marshal tells news outlets that firefighters have been pulled away from the scene because the gear has tested positive for hazardous materials. This is a cautionary measure until they can identify what chemicals they are dealing with.