The shooting happened at 3:54 p.m. on the 1900 block of West Olney Avenue, just off the campus of La Salle University.
The victim, identified as 22-year-old Adrian Wills, suffered a gunshot wound to his left torso. He was rushed to nearby Albert Einstein Medical Center where he was pronounced dead.
Police believe that the shooting stemmed from an argument in a rear alleyway.
The victim is not a student at La Salle, according to investigators, and had nothing to do with the university.
Police are scouring the area for a suspect. He is described as a black male, 18 to 25 years of age, 5'9"- 5'10", light complexion, scruffy beard, wearing a white thermal top, black pants, and a black skully. He was last seen running on foot north on the 5600 block of North 20th Street.
A number of people who witnessed the shooting were transported to Homicide headquarters for questioning.
Police say there were cameras in the immediate area, and are hopeful something was captured that will help lead them to the shooter.