A freight train derailed in Elgin, Ill., early Thursday, snarling the morning commute on Metra's Milwaukee West Line.

The Canadian National freight train derailed near Spaulding Road and Lambert Lane between Elgin and Bartlett, Ill., about 40 miles northwest of Chicago and 90 miles southwest of Milwaukee, at 5:10 a.m., local emergency officials said.

No injuries were reported, but at least two cars caught fire, and the Elgin and Bartlett fire departments were battling on-and-off blazes. Helicopter footage showed about 18 cars overturned.

The cause of the derailment is under investigation. A local NBC station reported that two freight trains had collided, but that had not been confirmed by police as of 9 a.m.

The accident has blocked all but one track on the Milwaukee West Line. Metra is running limited service between Bartlett and Chicago using trains that passed Bartlett before the derailment, but all other trains are stored in Elgin and can't be used until the accident site is cleared.

Metra spokesman Mike Gillis said he did not know when that would be. First the derailed cars have to be cleared, and then officials will have to determine if track repairs are needed. In the meantime, Metra recommends that commuters use Union Pacific lines instead.

It appears that the service disruption may be lengthy, the Metra Web site said. At this time, no train traffic can move through the area and we have no indication as to when service will resume. We advise all Milwaukee West Line customers to seek alternate transportation.

There were conflicting reports as to whether the train was carrying hazardous materials. Officials said it was carrying sodium hydroxide, or lye; ferrous sulfate, or iron; and organic acid. The Bartlett Fire Department told NBC Chicago that no materials had spilled, and officials had no plans to evacuate nearby residents.