It started around 5:30 p.m. inside a store on the 2200 block of Ridge Avenue.
Two officers responded to the report of a man armed with a knife.
"There was 49-year-old male in there, armed with a knife and he was chasing customers out of the store. There were about five or six customers in the store that this male chased out of the store with a knife," Chief Inspector Scott Small said.
Police say the man, possibly impaired, attempted to attack the officers with the knife.
Police say they Tased the suspect twice, but it did not stop him.
At least one officer opened fire, striking the 49-year old man in the back.
Authorities say the suspect still did not give up and the officers had to wrestle the knife away from the wounded man.
Medics responded and rushed the man to Hahnemann Hospital for care.
He is expected to survive.
Neither the officers nor anyone else in the store was hurt.