The cause of a fire at a Citgo oil refinery in a southwest Chicago suburb remained under investigation Thursday morning.
Officials said there were no injuries and no evacuations in the fire that started at about 7:40 p.m. Wednesday in the Lemont, Ill., refinery's crude oil unit.
"I know there was a lot of work being done at the refinery, something sparked, which caused the fire," Lemont Mayor Brian Reaves said.
Employees at the refinery said they heard a hissing sound and a loud explosion, which they believe came from an oil leak.
All of the refinery's employees were accounted for, said Reaves.
The crude oil unit was immediately shut down, and firefighters from Lemont and surrounding suburban departments helped bring the fire under control by 10 p.m.
"The refinery is conducting air monitoring and is working closely with Will County Emergency Management and local fire departments," the company said in a statement.
The vast refinery, at 135th Street and New Avenue, covers land in Lemont, unincorporated areas nearby and parts of Romeoville. The area around the refinery is not heavily populated, Reaves said.
When asked if the refinery has been a good neighbor to the citizens of Lemont, he responded: "Absolutely."