WYNNEWOOD, Okla. (AP) _ An explosion and fire erupted at a south-central Oklahoma refinery Friday afternoon, authorities said. There were no reports of injury, but authorities asked some residents to leave their homes.

News video from the scene showed fire burning in a section of the refinery, with water being sprayed on the flames. A thick column of black smoke was rising.

Mike Hancock, spokesman for the Wynnewood Refining Co., said there was an explosion in a sulphur recovery unit.

``The fire is being confined and we are going to let it burn itself out,'' he said.

He said there were no reports of injuries.

Residents east of the refinery and south of Oklahoma 29, were being asked to evacuate the area, said Betty Gabbard, a dispatcher with the Wynnewood Fire Department. She said the evacuation area represented about half of the town of about 2,500 people, 60 miles south of Oklahoma City.

``We've got officers doing house-to-house evacuations right now,'' Garvin County sheriff's Lt. Rodney Wright said. ``We don't know how bad the smoke is. We'd rather be safe than sorry.''

He said a sports complex west of town was serving as an evacuation center.

Jeff Benham, a truck driver from Odessa, Texas, said he was loadiing some supplies on to his rig at the refinery when the explosion occurred.

``It was plenty big,'' he said ``We heard it and everybody started running, so I started running, too.''

He said his 11-year-old daughter, Tori, was in his truck. He got her out of the vehicle, left it idling and left the area.

Hancock said the fire was not likely to spread to other areas of the refinery and he said there was not a public health hazard.

The fire began about 2:30 PM.

The refinery processes about 54,000 barrels of crude oil per day, and is considered a fairly small refinery. It employs about 200 people.