Bethlehem Star Baptist Church was celebrating its 25th anniversary on Sunday when someone started shooting at the church from an alley across the street.
Investigations are ongoing but the Police have revealed that the incident occurred just before 2pm and a 17-year old standing outside was hit in the leg.
A bullet also went through one of the church's window and grazed 24-year-old Damane Mitchell.
He told local reporters: "We just heard a blast and I felt something sharply hit me in the back of the head.
"Somebody at church told me that I was bleeding. I did feel the pain in the back of my head, so EMTs (Emergency Medical Technicians) came out and I guess they gave me something. It's just sad, you know?"
Mitchell's head was grazed by a bullet and he sustained a minor scratch.
He was at the church to attend his best friend's wedding.
The wedding and anniversary celebration for Pastor Roosevelt Watkins attracted dozens of people together from the neighbourhood.
Both victims were taken to hospital for treatment and are expected to "be ok", according to WGN-TV.
Police are yet to make any arrests in connection to the shooting and say witnesses are not cooperating.
