It happened on the 2500 block of N. 9th Street around 9:30 p.m. Tuesday.
Commissioner Christine Coulter says based on the evidence, investigators believe the victim was an innocent bystander.
"It certainly didn't look like she was the intended target. It didn't seem like she was involved in anything that would lead to her being shot. It's truly what keeps you up at night," said Coulter.
Neighbors say the 23-year-old victim was friendly and that she leaves behind a young daughter. Police identified the victim as Crystal Roman-Benitez.
At the scene, two types of shell casings were collected by police which may indicate that rivals were aiming for each other when the bullet struck the unintended victim in the head.
Police say a 54-year-old man also suffered a graze wound to the right shoulder.
"We believe that there was a second person that has a graze wound. They are being interviewed as a witness," said Coulter.
The shooter may have been in a car driving by at the time.
Police have secured video of a car driving by from a camera a few blocks away. They are in the process of interviewing the occupants of one car in particular.
On Wednesday night, dozens of people gathered to remember the young mother.
No arrests have been made.
Anyone with any information is asked to call police at 215-686-TIPS.