The incident happened shortly after 8 a.m. east of the Sayville station and involved a "trespasser," according to Metropolitan Transportation Authority Police.
No other information, including the victim's condition or identity, was released.
The collision shut down rail service along the Montauk Branch between Babylon and Patchogue for an hour. Passengers aboard the impacted train were transferred to another train.
Service on the line resumed at around 9 a.m. with residual delays.
MTAPD and LIRR supervisors are on the scene investigating.
Customers were advised to use the TrainTime app or visit the MTA website for the most recent service updates.
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