The victims told police they were visiting the home on Friday in Gary, Indiana when a man came up to them with a gun and demanded money.
Investigators said the suspect, Oasia Barnes, forced the teen's father to drive to an alley.
That is when they say he assaulted the man's 16-year-old daughter at gunpoint.
People living in the area said they are shocked by the crime.
Barnes is charged with rape, sexual battery, kidnapping and other charges.