Pittsburgh Police from Zone 5, Fire, and EMS responded to reports of shots fired outside the Walmart in the Waterworks Shopping Plaza just before 5:30 p.m.
Responding units located a vehicle outside the store that had sustained bullet holes after a dispute that possibly started inside Walmart, moved outside.
A man sitting inside the parked car was not injured and no gunshot victims were located. Police created a perimeter and evacuated shoppers from inside the store.
Officers received information that as many as three suspects fled in a vehicle and that another may have reentered the store. As police searched through adjacent businesses, SWAT operators conducted an extensive search of Walmart. No suspects were located inside. A ladder truck from Pittsburgh Fire was used to help police search the roof.
One female was treated by medics for a back injury sustained while evacuating the store.
The Crime Scene Unit processed evidence at the scene and the vehicle was returned to its owner.
The investigation is ongoing.