A woman was killed early Monday when she fell onto the tracks while trying to move between subway cars, cops said.

The unidentified straphanger, who police believe was in her 70s, was moving between cars just before 4 a.m. on a northbound N train when she fell onto the tracks as the train pulled into the 49th Street station, police said.

Her body was found on the tracks in the tunnel after the train left the station, cops said.

Police are investigating the incident.