The incident happened just before noon Saturday iniside a residence at 2238 Snyder Avenue near 22nd Street.
Police have arrested the landlord in the shooting.
The victim is a 47-year-old male.
He was transported to the Hospital of the University of Pennsylvania with multiple gunshot wounds, including one to the head.
He is listed in critical condition.
Police say the landlord initially took off on foot and was found not too far from the scene in a taxicab he was driving.
Charges against the landlord are pending.