Amtrak spokesman Cliff Cole said the Washington-bound Acela 2213 train struck an unidentified person on the middle express tracks - near the Hamilton station - just after 1 p.m. It was not immediately clear why the victim was on the tracks.
No one aboard the train was injured.
Both Amtrak and New Jersey Transit trains experienced delays ranging from 10 to 30 minutes for several hours as authorities investigated the accident. Trains were running on a normal schedule by Sunday evening.