A series of explosions early Friday tore through a Philadelphia gasoline refinery, the East Coast's largest, sending shock waves for miles and raining debris on nearby neighborhoods, just as the busy summer driving season was beginning.

Five minor injuries were reported, one by the fire department and four by refinery officials.

The three-alarm fire at the Philadelphia Energy Solutions refinery was contained but not under control, the fire department said. About 120 firefighters worked to cool off the areas around the fire to keep it from spreading.

The fire turned the sky bright orange and shook the homes of startled residents. Some neighbors in South Philadelphia said debris rained from the sky into their neighborhoods after the explosions, according to NBC Philadelphia.

The outage occurred as the U.S. summer driving season kicks into high gear.

Gasoline futures jumped 4% on Friday. Because RBOB futures reflect New York harbor prices, they are especially impacted by an outage in a refinery in Philadelphia, an important regional refining hub. In addition to the average $2.66 per gallon, pump prices on the East Coast could rise 3 cents to 5 cents per gallon as a result of the explosion, Wells Fargo said in a note to clients Friday.

Natural gas prices also rose 1% after the explosions.

"It's a serious outage that's going to greatly affect the East Coast in particular," said John Kilduff of Again Capital. "There's a cushion for drivers because we're well supplied, but if there's major damage, it's going to change that dynamic dramatically."

Gasoline demand in the U.S. reached a record high last week, according to government data released Wednesday. U.S. drivers consumed a record 9.9928 million barrels a day last week. That is up from the 9.3 million barrels a day used a year ago. It was also up from 9.877 million barrels a day the week earlier.