The period crime drama features a key action sequence in which mobsters open fire on cinemagoers in Grauman's Chinese Theatre on Hollywood Boulevard. Studio Warner Bros however decided to postpone the film's release and rework the scene following the Aurora cinema shooting in July.
The reshoots will commence on Monday, August 20, according to The Hollywood Reporter.
Insiders have said that the night shoot, which will take between three and seven days, will incorporate principal actors such as Ryan Gosling, Josh Brolin and Michael Pena. The action will be moved from Hollywood to Chinatown, in order to save on set dressing time.
Warner Bros has declined to comment on the reports.
Gangster Squad will now open on January 11, 2013.