The second largest crude distillation unit (CDU) was shut by a fire on Sunday at Phillips 66's 330,000 barrel-per-day (bpd) joint-venture Wood River, Illinois, refinery, a source familiar with plant operations said.
One person was taken to a local hospital with burns, the source said.
The 120,000 bpd DU-2 CDU was returning on Sunday to production after an overhaul when the fire broke out, the source said.
Phillips 66 spokesman Joe Gannon said in an email that the injured person walked to the ambulance. All other employees and contractors working at the refinery have been accounted for.
Local and social media reports said there had been an explosion at the refinery, 23 miles (37 km) northeast of St. Louis.
"At approximately 4:30 p.m. CST (2230 GMT) on Sunday, February 10, there was an event at the refinery that resulted in a fire in one of the process units," Gannon said. "The fire is isolated and under control."
St. Louis television station KMOX-TV said the person's injuries were not life-threatening.
The Wood River refinery is a 50-50 joint venture between Phillips 66 and Cenovus Energy Inc. Phillips 66 is the managing partner.