An Amtrak passenger train rammed into the back of a freight train in Chicago on Friday, injuring at least five employees, fire officials said.
Up to 150 passengers were on the Amtrak train when it came to a "very hard stop," said Fire Department spokesman Larry Langford.
Langford said that it was unclear what caused the accident.
Passengers, many of them carrying luggage, streamed off the trains with the help of rescue workers. Most walked away from the accident — some holding the hands of small children — but some were taken away on stretchers.
The five Amtrak employees who had serious or critical injuries were in the train's engine at the time of the collision, officials said.
The engine of the Amtrak train was resting on top of the last car of the freight train, but the Amtrak passenger cars remained upright.
The red freight train's corrugated boxcar was crushed.
Most of the damage was concentrated on the passenger train's engine, Langford said.
The train 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.