Derailing at O'Hare International Airport, the train crossed a platform and eventually landed halfway up an escalator.
Although 32 people sustained injuries, no one was seriously harmed because it occurred at 3am when fewer people were around than usual.
The president of Chicago transit union told reporters that the train operator was "extremely tired" and may have dozed off, leading to the train coming off the tracks.
Passenger Denise Adams was quoted in The Sun talking about the dramatic crash: "I heard a 'boom' and when I got off the train, the train was all the way up the escalator. There was a lot of panic."
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