The Associated Press

BIG SPRING, Texas — An explosion rocked an oil refinery Monday in a violent blast that shook buildings miles away and injured at least one person, the company said.

All workers were accounted for about an hour after the explosion, said Blake Lewis, spokesman for refinery owner Alon USA. The injured worker was in the hospital, but the person's condition was not known, Lewis said.

The fire sparked by the blast was under control Monday morning, Lewis said. The Dallas-based company does not know what caused the explosion, he said.

The blast sent black smoke billowing into the sky, closed schools, shut down a major interstate and left residents rattled.

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

John Moseley, managing editor of the Big Spring Herald whose downtown office is also about two miles from the refinery, said, "I thought it would knock the walls down."

Two elementary schools were evacuated, then classes were canceled at all nine campuses in the Big Spring school district, assistant superintendent Carie Dunnam said.

The explosion forced open the doors of the school district's administration building about four miles from the plant, Dunnam said.

"Literally pieces of my ceiling came on top of my head," she said.

Bus routes were affected by road closures and that emergency officials were warning of the potential for more explosions, Dunnam said. Parents were asked to pick up their children, she said.

The refinery employs about 170 people and produces about 70,000 barrels a day.

Interstate 20 was shut down near the plant, Big Spring police spokesman Roger Sweatt said.

"There's some fire and a whole bunch of smoke," Sweatt said.

Big Spring is about halfway between Dallas and El Paso.