It happened just after 7 p.m. on Wednesday.
Investigators say the gunman and the 35-year-old victim, identified as Vaswani Brown, were seen on surveillance arguing inside the Fresh Mini Market at Summerdale and Magee avenues.
The altercation spilled outside, with the suspect opening fire as Brown got into his SUV.
Brown was rushed to Jefferson Torresdale Hospital, where he later died.
Police found a gun belonging to the victim at the shooting scene.
Jose Espinal, who owns Fresh Mini Market, spoke to Action News. He says he was returning from the gym and came up on the suspect and Brown arguing.
Espinal says he tried to tell them both, who he knows as regular customers in his store, that life is good and he attempted to defuse the argument before walking into his store.
The violence, however, escalated outside and the suspect pulled out his gun.
Espinal says Brown was a father who lived in the neighborhood and he feels for the children.
No arrests have been made. The shooting remains under investigation.
Anyone with information can call or text Philadelphia police at 215-686-TIPS (8477) or submit an anonymous tip online.