Police believe the woman was not part of the argument and the bullet was not meant for her.
The shooting happened around 1:30 p.m. Saturday at a deli that sits on a triangle where Ridge and Cecil B. Moore avenues and 23rd Street intersect.
Police say the gunman fired the shot from the entrance on the Cecil B. Moore side.
The woman was taken to Hahnemann University Hospital. She was pronounced dead at 2 p.m.
A person of interest was taken into custody at the scene. Police say they received more information about a second person of interest at another location.
They rushed to that location and placed another male into custody.
Residents watched as the police processed the scene. Many were fearful of talking and fed up with violence on this North Philadelphia block.
"They need to put these guns down. Put them down. We're afraid to come out of the house now. I come to the store I go right back to my house. I'm scared to sit on the step now," said one resident.
No weapon was found at the scene and police are working to identify the shooter.