Natural gas (search) exploded at an underground storage facility before dawn Thursday, forcing dozens of people from their homes, authorities said.

No injuries were reported, but roads were closed and houses were ordered evacuated within a mile of the Duke Energy (search) site, about 40 miles northeast of Houston.

Witnesses said in broadcast reports that they saw a ball of fire from a bridge over the Trinity River (search).

One person who was inside the storage site when the gas exploded managed to escape, said Capt. Bill Tidwell of the Liberty County Sheriff's Department.

"Everybody's been accounted for," he said.

Crews initially decided to let the gas burn itself out, but authorities later said that would take too long. Experts at capping blown-out wells were called in to examine how to cool down and control the fire.

Two other storage chambers at the facility were not thought to be threatened, Tidwell said.

The cause of the explosion had not been determined.

Danny Gibbs, a spokesman for Charlotte, N.C.-based Duke Energy, said there were no environmental or safety concerns. "Natural gas is burning, but it will dissipate," Gibbs said.

The sparsely populated area is dotted with manmade caverns inside salt domes, the world's largest storage site for explosive hydrocarbons. In 1980, an underground gas leak in nearby Mont Belvieu forced 72 families from their homes for almost five months.