CHICAGO (AP) -- An Amtrak train collided with a freight train Friday on Chicago's South Side, possibly injuring as many as 100 people.

The tracks do not carry Metra or South Shore trains, which will not be impacted during the afternoon commutes, officials with both passenger train services said Friday afternoon.

Train No. 371, known as the Pere Marquette, was traveling from Grand Rapids, Mich., to Chicago when the accident occurred in a rail yard south of Union Station, Amtrak spokesman Marc Magliari said.

The train was scheduled to make stops in Holland, Gangor, St. Joseph-Benton Harbor and New Buffalo before arriving at Chicago's Union Station at 10:30 a.m.

"So far nobody is being taken on stretcher. That's a good sign," said Fire Department spokesman Larry Langford. "It looks like everybody is walking."

The engine of the Amtrak train was resting on top of the last car of the freight train in the neighborhood known locally as Fuller Park. The Amtrak had three double-decker passenger cars, Langford said.

Langford said that it was unclear what caused the accident, only that the two trains were on the same track.

Fifteen ambulances and a fire-suppression unit were at the scene tending to passengers, and rescuers were inside the train working to assess passengers, officials said.

Firefighters could be seen leading passengers away from the train, some of them children holding the hands of adults. Most were walking, but at least one person was taken away by emergency workers on a rolling upright stretcher.

Most of the damage was concentrated on the passenger train's engine, and no one was in the portion of the freight train that was struck, Langford said.

"The passenger cars look to be in great shape, great shape," Langford said.

Information about the conditions of those on the train is available to loved ones through a hot line established by the American Red Cross at (312) 729-6200.

Know anyone on the train? Contact Times Staff Writer Kirsten Srinivasan at kirstens@nwitimes.com.