The explosion at BP Corp.'s Whiting Refinery occurred at 6:20 a.m. and left two employees and a contractor with apparently minor injuries, BP said in a statement issued by its New York office.
``I live a little less than a mile from the refinery and it shook my house,'' Whiting police Sgt. Donald Greer said.
Emergency personnel ``could see a big ball of fire,'' but the fire was quickly brought under control, Greer said.
The BP statement said hydrogen gas in a unit apparently began to burn, but was contained by the refinery's firefighters. The city's Fire Department was not called in to assist.
``The unit has been isolated and shut down,'' the company's statement said.
BP spokeswoman Camille Dass said she had no immediate information on any production loss that might result from the fire.
The refinery along Lake Michigan near Chicago processes more than 400,000 barrels of crude oil daily. Gasoline makes up half of the 16 million gallons of products it produces daily, the refinery's Web site states.
Two of those injured in the fire were BP employees, one who received first aid for burns and another who suffered a back injury, BP said. A contractor was taken to a nearby hospital with apparent shoulder injuries, the statement said.
