BIG SPRING, Texas
-- A thunderous explosion rocked an oil refinery Monday, injuring five people and shaking buildings miles away.

One employee was hospitalized for burns, while three contractors were treated and released, said Blake Lewis, a spokesman for refinery owner Alon USA.

A fifth person was injured when her car was struck by debris on Interstate 20, Big Spring Mayor Russ McEwen told the Odessa American. She was treated and released from a hospital.

Fires that lingered after the blast were extinguished late Monday afternoon, Lewis said. The next step will entail getting into the site to determine what happened and how to make repairs.

Lewis said all workers were accounted for about an hour after the explosion.

A skeleton crew of just 40 people were there Monday because of the Presidents Day holiday, Alon USA Vice President David Foster told the newspaper. There are typically about four times as many people on duty at the time of the explosion, he said.

Foster said he expected the refinery to be offline for weeks.

The blast sent black smoke billowing into the sky, and forced the closure of schools and an interstate.

"It was extremely scary. You shook you were so scared," said Laura McEwen, the mayor's wife, who lives about two miles from the refinery. "Our walls shook. It jolted your bed. It was like an earthquake."