A 19-year-old woman was allegedly raped by a stranger on the staircase of the West Fourth Street-Washington Square subway station in the West Village early Tuesday morning, police sources said.

The woman said she was on the staircase around 3:40 a.m. when an unknown man came up behind her, pulled down her shorts and raped her, sources said.

She reported the incident to police later that day and the NYPD’s Special Victims Unit is now investigating.

Additional reporting by Gabrielle Fonrouge