An explosion hit an oil refinery plant in the U.S. state of Texas on Monday, and it is still unclear if any casualty was resulted, according to a CNN report.

Citing witnesses, the TV said that the huge rock shook houses miles away from the oil refinery plant in Big Spring, about midway between Dallas and El Peso.

Russ Mceman, the mayor of Big Spring, told CNN "no indication whatsoever" what caused the explosion and his understanding is that "no one has died in the blast."

The refinery owner, Alon USA, said that at least one worker was reported hurt but his situation remains unknown.

All workers were accounted for about an hour after the explosion, according to the company's spokesman, Blake Lewis.

According to the Dallas-based company, the refinery employs about 170 people and produces about 70,000 barrels a day.