Updated

A freight train struck the rear of another freight train in southwest Chicago early Sunday, derailing several rail cars and damaging a third freight train on an adjacent track, authorities said.

Local reports said power was briefly knocked out to more than 2,500 people in the surrounding area.

There were no immediate reports of any injuries following the derailment shortly before 2 a.m. CDT Sunday, CSX rail spokesman Bob Sullivan told The Associated Press.

The derailment sent eight full-sized cars off the tracks and one slid down an embankment into a nearby backyard," a Chicago fire official and media affairs director, Larry Langford, told The Chicago Sun-Times.

At least one of the trains was carrying liquid waste, Langford told the newspaper. The report said emergency crews initially called for a hazardous materials response as a precaution, but no hazardous materials were detected and no leaks discovered.

Sullivan said one train formation bound from Nashville to Chicago had two locomotives and 13 freight cars; another from Albany, N.Y., to Chicago had four locomotives and 93 freight cars and a third on a route from Flint, Mich., to Chicago had two locomotives and 130 freight cars.

But he said he had no specifics on which train hit the other and which was on the adjacent track. He also said rail officials were at the site investigating and he had no immediate information on any loads or cargo aboard the trains.

"CSX is working with local first responders gathering additional information," he told AP, adding the derailment remains under investigation.

He added that the primary focus remained on public safety.

Some local reports initially said the derailment occurred in an area of elevated tracks, but Sullivan said he had no comment on those reports.

Local radio and press reports said several city blocks had been blacked out in an area in Chicago's southwest early Sunday. An energy provider, ComEd, did not immediately answer calls seeking further details. ComEd's online map of power outages indicated one early Sunday had affected more than 2,100 customers in the same area.