Officers arrived at the pizza parlor while the suspects were trying to pull off the robbery.
A strike force officer got to the back door and a 35th district officer was on the front door.
The suspects tried to run out the back door, police say, and one suspect shot at the officer, and the officer shot back.
Neither was hit.
Arrested were Christopher Martin and Quintrell Reynos both of the 6000 block of North 21st Street.