It happened at 1:30 p.m. Friday.
Police tell Action News two masked men with guns walked in and began robbing customers at Little Caesars Pizza at Island and Elmwood Avenues.
They say another customer walked in on the robbery. The two suspects then fled on foot.
Police say that customer followed the men out the door and called 911 while chasing them.
Police responded and caught up with the suspects in the 2600 block of Lloyd Street.
They say one of the suspects ducked behind a car and allegedly pointed a gun at police.
One officer opened fire, firing five shots and hitting the suspect several times in the midsection.
The suspect was taken to the Hospital of the University of Pennsylvania in critical but stable condition.
His alleged accomplice got away on foot. He remains at large.
Police Internal Affairs is investigating.