They say she was not the intended target.
It happened at the 54th Street Lounge on the 5300 block of Wyalusing Avenue around 1:30 a.m. Thursday.
Police say the 63-year-old woman was sitting at the bar when someone opened the door and fired three shots inside.
"We found three spent shell casings inside the bar right by the front door," Philadelphia Police Chief Inspector Scott Small said.
The woman was hit in the leg. She was taken to Penn Presbyterian Medical Center in stable condition.
Police say there were five customers and two employees inside the bar at the time. No other injuries were reported.
About an hour before the shooting, police received a call about a fight involving two people and gunshots at the same location.
They believe the shooting may have stemmed from that incident.
Investigators are looking at surveillance video from the bar and the neighborhood.
No arrests have been made.
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