Employees have been evacuated from National Copper and Smelting Co. after a furnace exploded. The business was closed after the explosion.

Huntsville Fire and Rescue's hazardous materials team responded. There were no injuries.

Huntsville Fire says the furnace exploded while it was attempting to be lit.

Crews are working to get natural fumes out of the building, 3333 Stanwood Blvd.

An employee, Mary Thomas, said it was unlike anything she'd ever seen.

"It was like a boom and a bunch of black smoke. They were telling everybody to run, and we had to get out of the building real fast," she said.

She explained the incident happened late enough in the day that many people had already gone home.

"The people that work on the end of the furnace, they already had gone home, and that's the main thing we were worried about, that they wast in there," she said.

Thomas said if the employees were still there when the explosion happened, then the situation could have been deadly.

"This had to be God," she said.

The explosion was ruled an accident. Huntsville Utilities was called out to turn off gas to the building. WAAY 31 was told it won't turn back on until the building is inspected.