PASCAGOULA, Miss. — Authorities are investigating the cause of an explosion and fire at a southern Mississippi refinery that killed one worker.

Chevron Mississippi general manager Tom Kovar says an operator in the Cracking II Processing Unit was killed this morning. He identified the victim as Tonya Graddy, who lived in Alabama. He says Graddy had worked at Chevron for five years.

Kovar says Graddy was among about a dozen workers in the area when the explosion happened.

The cracking area of the refinery is the first step in breaking down crude oil into various components so it can become gasoline or coke. It’s a hot process and furnaces are involved.