It happened near the intersection of Haddon and Kaighn Avenues in Camden around11:30 last night.
Police say the gunman was chasing 24-year-old Carlton Carney, when Carney jumped into the woman's car. The gunman opened fire, hitting Carney and the 18-year-old woman.
Carney was killed.
The woman is in stable condition at Cooper University Hospital with a gunshot wound to her back.