Watch: Gunman stalks teen girl walking dog in Philadelphia before deadly shooting

Authorities in Philadelphia released new video showing the deadly shooting of a teenage girl who police say was killed while walking a dog with another person over the weekend.

Investigators say 17-year-old Teryn Johnson was on the 5300 block of Harrock Street just before 9 p.m. Sunday night when she was shot in the chest by and unknown gunman. 

Responding officers from the Philadelphia Police Department drove Johnson to Temple University Hospital where she died a short time later, according to investigators. 

Video shared by police on Wednesday shows the suspected shooter and a getaway car stalk the victim's path before carrying out the deadly shooting. 

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Investigators say the shooter and at least one other person inside a dark-colored Dodge Challenger waited on a street corner for at least two minutes while the victim and her friend pased. 

The gunman, dressed in dark clothing wearing a nearly full head covering, eventually exits the car and hides behind a parked van after the victim walks by. 

The multi-angle montage of surveillance footage shows the Challenger pick up the shooter and drive a short distance down the street where he exits the vehicle and fires at least three times. 

Officials are offering a $20k reward for information that leads to an arrest and conviction. 

"It certainly appears that our decedent was specifically targeted," Captain Jason Smith from the Philadelphia Police Department told reporters at a Monday press conference.

Neighbors who rushed to the aid of Teryn said she was hit at least seven times in her chest and side. 

"It’s not right, they took my daughter from me, ain’t no parent supposed to outlive their child," Paul Johnson, Teryn's father, told FOX 29.