Contractors worked through the night scraping away burned asphalt and repaving an 800-foot swath of Interstate 77 charred by a massive natural gas line explosion and fire that also flattened four homes and damaged five more but caused no deaths.

The Tuesday afternoon blast between Sissonville and Pocatalico, about 15 miles outside the capital city of Charleston, melted guardrails, cooked the green enamel off highway signs and burned utility poles, while leaving a huge hole in the highway.

The northbound lanes reopened early Wednesday and traffic began flowing on the southbound lanes a few hours later.

Though several people were treated for smoke inhalation, no serious injuries were reported either on or off the major commuter route.

But hours afterward, respiratory therapist Sancha Adkins was still shaky. She was heading north toward a patient's home in Ripley, a tractor-trailer behind her, when a flash alongside the highway caught her eye.

"And then I just see this whole huge ball of fire, and I'm slamming on the brakes and pulling off to the side of the road, and then the flames come across the road in front of me," she said, still breathless and nearly hysterical hours later. "I saw parts of something — I don't know what it was, a house maybe? — exploding."

A wall of flame roared across the highway about 150 feet in front of her car, she said, and she tried to back up on the shoulder. So did the truck behind her, which was able to stop without rear-ending her vehicle.

"But that wasn't fast enough for me," said Adkins, 36, of St. Albans. "I did a U-turn in the middle of the road and literally drove the wrong way on the interstate. I had my hazard lights on flashing, just trying to tell people to get out of the way."

There was oncoming traffic as she hugged the berm on the median.

"I didn't care," she said. "It wasn't as bad as that explosion."

Adkins traveled about 2 miles, got into an emergency lane and got off at the nearest exit, onto Route 21, still bound for Ripley. Then she realized she was still heading toward the flames.

"I don't think it clicked until then. I was hysterical and crying and flipping out," she said.

She tried to dial 911 three times, she said, but couldn't get the numbers right. Eventually she called her office and told them what happened.

"I'm incredibly lucky I didn't die in a fire," she said as she tried to unwind at a hair salon Tuesday evening.

Officials marveled that no one was killed.

"We've been very fortunate," said Gov. Earl Ray Tomblin, after seeing the collapsed and charred houses. "They were just lucky enough not to be home."

Most of the neighborhood's residents were at work or school. One man, Tomblin said, had just left to go hunting.

Federal and state agencies are now investigating what caused the explosion in the 20-inch transmission line owned by NiSource Inc., parent company of Columbia Gas. The gas flow was shut off, but residents who lived within 1,000 feet of the fire zone were evacuated as a precaution.

Kent Carper, president of the Kanawha County Commission, said flames were shooting some 75 feet into the air before the fire was extinguished.

"It sounded like a Boeing 757. Just a roar," he said. "It was huge. You just couldn't hear anything. It was like a space flight."

Carper said the flames spanned about a quarter of a mile and ran through a culvert under the interstate.

"It actually cooked the interstate," he said. "It looks like a tar pit."

NiSource spokesman Mike Banas said the company was still gathering facts and no effects on customers were expected.