Online images show the train at a slight angle in its track bed in the busy Atlantic Terminal.
Passengers told TV news crews on the scene that there was a loud bang and a jolt that sent some people flying.
Some people were carried away on stretchers. Others were sitting outside the train holding ice packs to their heads.
Reports from the scene said some people were bleeding from cuts.
Railroad officials said they had no immediate information on the cause of the accident, which happened at around 8:20 a.m. Wednesday.
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