It happened on June 28, around 4:22 p.m., on the 200 block of E. Cambria Street in the city's Kensington section.
Police say a 21-year-old woman was found suffering from a gunshot wound to her stomach. She was pronounced dead at Temple University Hospital.
On Monday, police released surveillance video of a group of three women and a man wanted for questioning in connection with the homicide.
The suspects were operating a silver Jeep Cherokee with Pennsylvania tags LRW-5401, said police.
A $20,000 reward is being offered for information that leads to the arrest and conviction in the case.
Anyone with any information is asked to call police at 215-686-TIPS.