A downed power line sparked an underground gas line near Roosevelt Road on Tuesday, setting of an hours-long flame so hot it melted the surrounding concrete.

No one was injured and no buildings were damaged by the fire, but the resulting power outage snarled traffic during the afternoon rush hour.

The blaze began soon after 4:30 p.m., when emergency officials responded to the report of a downed power line at 17 Sunset Ave., northwest of the Roosevelt Road and Main Street intersection. When fire crews arrived they saw the live wire arcing on the driveway entrance of an apartment building.

Within minutes, the power line penetrated the driveway and ignited an underground gas line, the Glen Ellyn Volunteer Fire Co. reported.

“It just caught on something — a gap in the concrete,” said Craig Eldridge, spokesman for the fire company. “Literally, the electricity then went down through the concrete.”

After an initial fire ball, the blaze burned steadily for several hours before workers with Nicor gas company could stem the flow of fuel. As a precaution, emergency officials evacuated five nearby buildings.

The downed power line meant about 300 customers as well as Roosevelt Road traffic signals were without electricity that night. Power was fully restored by Wednesday morning, a spokesman for ComEd said.

Fire officials are not sure what brought the power line down, and they likely will never know with certainty, Eldridge said. As for the gas line ignition, it was the product of rare circumstances.

“There’s a lot of freak occurrences here,” he said. “It was a major (electrical) line carrying a lot of power. … It kind of hit the perfect place for the electricity to penetrate down into the ground.

“Power lines fall on top of underground gas lines all the time and nothing happens.”