The victim was struck near the Glen Rock Borough Hall train station at 9:22 a.m., NJ TRANSIT said.
Authorities couldn't immediately address reports that he may have parked at the station and then jumped from the platform.
The No. 56 Bergen Line train had left Port Jervis at 7:39 a.m. and was scheduled to arrive in Hoboken at 9:52 a.m.
There were no reported injuries to the crew and 100 or so aboard, a spokesman for the agency said.
Nearby trains were temporarily stopped but have since resumed, he said.
Members of the Glen Rock Fire Department and Valley Hospital Paramedics responded to assist borough and transit police, Glen Rock Police Chief Dean Ackermann said.
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