The person was struck at about 9:30 a.m. by an express train headed for New Haven, said Meredith Daniels, a Metro-North spokeswoman. That train was not due to stop at the Cos Cob station, she said.
Daniels had no further details on the accident or the victim.
MTA and Greenwich police are at the scene and investigating.
The passengers on the New Haven-bound train where transferred to another train and were on their way shortly after 10 a.m., Daniels said.
Metro-North's New Haven Line service is experiencing delays of 15 minutes due to police activity in the vicinity, she said. There are speed restrictions on trains in the area.
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