The movie chronicles the events surrounding the bombing and the manhunts that took place afterward from the perspectives of first responders, hospital workers, every day citizens and survivors.
Chicago Police Superintendent Eddie Johnson and 200 off-duty uninformed officers watched the film at the AMC River East 21 Theater in Chicago's Streeterville neighborhood.
The special advanced screening was to thank the men and women of the Chicago Police Department for putting their lives on the line every day at work.
"Patriots Day" premieres in theaters on January 13.