The victim, identified as 24-year-old Dasir Timbers, was shot in the head at 32nd and Clearfield streets in North Philadelphia around 8:20 p.m. on Tuesday.
Timbers was found lying on the sidewalk near St. James School.
He was taken to Temple University Hospital, where he was pronounced dead.
Police have been searching the grounds for ballistic evidence.
Real-time crime cameras recorded a man dressed in dark clothing approaching the victim, according to police.
Detectives will also be reviewing school surveillance as they search for the killer.
At this time, no suspects have been identified, and no arrests have been made. The investigation remains active and ongoing with the Homicide Unit.
Anyone with information regarding this incident is urged to contact the Philadelphia Police Department's Homicide Unit or submit an anonymous tip. As with all homicides in the city of Philadelphia, a $20,000 reward is available for information leading to an arrest and conviction.