The robbery occurred at the Go-Lo Gas Station at 1958 West 47th Street at about 1:55 p.m. on July 11, police said.
Police said an employee confronted a man in a blue Cubs shirt for allegedly concealing an item under his clothes. That's when he hit the employee in the face.
Staff locked the door and called police, but the suspect broke the glass door and ran off.
Anyone with information is asked to contact Area Central RBT Detective Toner #20350 at 312-747-8227.