LEMONT, Ill. (CBS) — A fire overnight at an oil refinery in southwest suburban Lemont could affect prices at the pump in Chicago.

CBS 2’s Susanna Song reports gas experts said wholesale prices rose 9 cents per gallon because of the fire at the Citgo refinery in Lemont, though drivers won’t necessarily notice the impact at the pump. That’s because wholesale prices already had dipped earlier this week.

READ MORE: Former Chicago Park District Supervisor Mauricio Ramirez Charged With Sexually Assaulting 16-Year-Old Lifeguard

Those two changes in wholesale gas prices effectively cancel each other out, meaning drivers won’t see the much of a change in prices at the pump next week.

According to AAA, The Citgo refinery is one of three suppliers of a specific blend of low-emission gasoline required by law in Chicago.

READ MORE: Joel Quenneville Meets With NHL Commissioner Gary Bettman Over Handling Of Blackhawks Sexual Assault Scandal

The blaze started around 7:40 p.m., and the refinery’s crude oil immediately was shut down.

The flames spread quickly, lighting up the night sky, as firefighters spent nearly two hours getting the fire under control.

“I know there was a lot of work being done at the refinery, something sparked, which caused the fire,” Lemont Mayor Brian Reaves said.

No one was injured in the fire.

MORE NEWS: 'Survivor' Contestant Michelle Yi Describes Frightening Santa Monica Assault

The refinery was conducting air monitoring at the site Thursday morning, to ensure the safety of refinery workers and nearby residents.