Flames and smoke poured into the sky Saturday over an oil refinery where lightning set off a fire and an explosion that was felt miles away, authorities said.

No injuries were reported and there were no immediate evacuation orders in the south-central Oklahoma town, said Mike Hancock, a spokesman for Wynnewood Refinery Co.

Flames and smoke boiled hundreds of feet into the air from two 80,000-gallon tanks in the Wynnewood Refinery complex, officials said.

Firefighters doused the area surrounding the tanks Saturday, Hancock said.

"Tank fires are pretty pesky fires. They're easy to keep contained, but they're hard to fight," Hancock said. "It's hard to estimate how long it will be. It can take a day or so to burn the product."

The fire started Friday when lightning hit a tank containing naphtha, an unrefined form of gasoline, fire Chief Ken Moore said. City and company fire crews sprayed foam on the blaze and transferred naphtha out of the tank, but hours later the explosion — felt by residents of communities several miles away — spread the flames to a second tank, authorities said.

Moore said the explosion may have followed the collapse of the first tank. "This allowed some of the (naphtha) to flow out and flow around the second tank," he said late Friday.

One tank contained about 50,000 barrels of highly flammable naphtha and the second tank contained about 30,000 barrels of diesel fuel, Hancock said.

Nearby highways were closed as a precaution, Moore said. He said the nearest homes were a quarter-mile from the refinery.

The refinery processes about 50,000 barrels of oil a day and employs about 185 people.

It is the second fire at the refinery — which produces gasoline, diesel fuel, military jet fuel, solvents and asphalt — in less than two years. A blaze in May 2006 led to the evacuation of 150 nearby residents. An acid leak a week later related to fire damage caused more evacuations.

The Occupational Safety and Health Administration issued 22 violations over that incident.

Wynnewood is about 65 miles south of Oklahoma City.