An explosion caused a large fire at a west Tulsa refinery in the U.S. state of Oklahoma early Thursday, local media reports said.

The Fire Department of Tulsa, the second-largest city in Oklahoma, received news of the fire at the HollyFrontier Corp. refinery shortly before 2:30 a.m. local time, and the large fire could be seen from the east side of the Arkansas River, according to reports on the website of News Oklahoma.

According to the reports, the fire appeared to be put out by 5 a.m. local time, but the damage the fire had caused to the refinery was not available yet.

The cause of the explosion was also not immediately known.

In April 2011, the refinery's Tank 13 also had a fire, which was blamed on a bad valve that allowed hydrocarbons to slip into the wrong tank.

HollyFrontier Corp.'s two Tulsa refineries can process diesel, jet fuel and other petroleum products with a capacity of up to 125, 000 barrels per day, said the reports.