The person was hit just before noon by southbound train #142 on tracks at the Oak Grove Avenue crossing, Caltrain said on social media.
There were 15 passengers on the train at the time, but no other injuries were reported.
All trains in the area were temporarily stopped but shortly before 1 p.m. both northbound and southbound tracks were cleared to move.
Passengers for train #142 at the Menlo Park Station will be accommodated by train #146, Caltrain said.