Exxon Mobil refinery in southwest suburban Channahon, Illinois investigating Sunday power outage

The Exxon Mobil refinery in southwest suburban Channahon, Illinois, said it trying to find what caused a major power outage on Sunday.

Officials with the refinery experienced a power outage at around 3:30 p.m. Sunday, resulting in a shutdown. Power was subsequently restored at about 7 p.m.

Monday, workers are the refinery are now conducting a site status assessment to determine the cause of the power outage. The spokesperson said they are in touch with the appropriate agencies.

The refinery said it is also conducting air monitoring.

"The safety of the community and our workforce remains our primary focus," the spokesperson wrote in a statement.