Hollywood film studios have put their usual box office rivalry on hold in the wake of the massacre at a midnight premiere of the new Batman movie.

Warner Bros decided to delay publishing weekend box office figures for The Dark Knight Rises after the Denver shootings that left 12 people dead and dozens injured.

Its major Hollywood rivals, Disney, Fox, Sony, Lionsgate and Universal, quickly followed, all wary of offending the public.

Warner also cancelled red carpet events for the film in France, Japan and Mexico.

The studio also scrambled to pull a trailer for another film, Gangster Squad, which included a scene in which mobsters shoot at theatre audiences.

Friday's massacre, in which a black-clad gunman gunned down dozens of filmgoers at a screening of The Dark Knight Rises, is a marketing nightmare for the film's makers.

Within hours they had canceled the movie's Paris premiere, which was to have been accompanied by a press junket with the cast and crew including director Christopher Nolan and star Christian Bale.

On Saturday Bale, who plays Bruce Wayne aka Batman, said: 'Words cannot express the horror that I feel .. ..I cannot begin to truly understand the pain and grief of the victims and their loved ones, but my heart goes out to them.'

Warner issued a statement early on saying it was 'deeply saddened'.

Then a spokeswoman confirmed that the studio will not publish weekend takings - a form of crowing about box office success - until Monday.

Unofficial figures from the industry daily paper Variety suggest that it made $US75 million ($A72 million) on Friday alone, the third biggest opening day ever at the US box office.

The Hollywood Reporter reported that The Dark Knight Rises, the climax of the blockbuster trilogy, was set to make $US165-170 million ($A159-163 million) over the weekend.

If confirmed, that would make it the second or third highest debut weekend ever, after this year's blockbuster Marvel Avengers Assemble on $US207.4 million ($A199.9 million), and level with Harry Potter and the Deathly Hallows Part 2, on $US169.2 million ($A163 million) last year.

'Out of respect for the victims and their families, Warner Bros Pictures will not be reporting box office numbers for The Dark Knight Rises throughout the weekend,' said a spokeswoman.

Separately, Warner was forced to scramble to cut a trailer for Gangster Squad, a 1940s mobster movie starring Sean Penn, Emma Stone and Josh Brolin, because of a shooting scene eerily similar to the Colorado massacre.

It had featured in a trailer package running before The Dark Knight Rises but not at the Aurora cinema where the shootings occured.