The Massachusetts Bay Transportation Authority says the person became trapped at the Central Square station in Cambridge just after 7 a.m. Thursday.
The Cambridge Fire Department says the person was alert and conscious when taken to the hospital. The extent of the victim's injuries was not disclosed.
The person's identity was not made public.
The MBTA stopped trains and both directions and shut off the third rail, which provides power. Shuttle buses were used instead.
Trains started rolling again at about 8 a.m., but there were residual delays.
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