HARVARD, Ill. (AP) -- Union Pacific crews are beginning to replace about 400 feet of railroad track damaged in a northern Illinois train derailment.

Railroad spokesman Mark Davis says it will take most of today to deal with a derailed tanker car containing ethylene oxide. That's a flammable material widely used to sterilize medical supplies. The tanker isn't leaking.

Davis says the line may not reopen until Friday. It handles a couple of freight trains daily.

Yesterday's derailment happened near the city of Harvard in northern Illinois.

The train was traveling from North Lake (Illinois) to Janesville, Wisconsin.