The incident unfolded around 3:00 a.m. Sunday on the 2000 block of Margaret Street.
Arriving officers discovered a 21-year-old man and his 20-year-old sister suffering from gunshot wounds outside their home.
Several neighbors reported seeing a male riding a bicycle from the scene.
Police soon discovered a bicycle fitting the description in the 4600 block of Ditman Street, as well as a suspect who matched the description of the shooter given by neighbors.
An officer attempted to stop the man, but he continued running and ran into an alley in the rear of the 4700 block of Frankford Street.
That's where, authorities say, the suspect pulled a gun and pointed it towards police.
The pursuing officer opened fire striking the 22-year-old suspect once in the back.
The two victims and the suspect were taken to local hospitals for treatment.
The brother and sister are both in critical but stable condition.
The suspect remains in stable condition.
Police are continuing their investigating and looking into the possibility of a second gunman.