An audience of cinema-goers in a packed evening screening nibble popcorn and swig soft drinks, watching the latest big-screen Hollywood spectacle before unthinkable violence sends the room into bedlam. Four men in trench coats, armed with submachine guns, stand behind the screen firing randomly into the crowd. As viewers clamber for the exits, the men hold onto their triggers and march forward in unison as a torrent of bullets tears the place apart.

That’s not a description of the tragedy that hit the Century 16 cinema complex in Aurora, Colorado, last Friday when 24-year-old James Holmes allegedly gunned down 12 people and wounded more than 50 on a shooting spree during a screening of The Dark Knight Rises. It is a scene in the trailer for new film Gangster Squad, a 1940s-set mob drama starring Sean Penn and Ryan Gosling. The trailer was set to play “loose” (industry parlance to describe a distributor’s request to screen) at around 30% of cinemas showing the Batman movie over the weekend. It is not known whether the trailer played at Century 16.

Deadline Hollywood reports that at 5am on Friday, roughly five hours after the shooting spree, a Warner Bros. executive remembered the scene from the Gangster Squad trailer and an hour later word came from the distributor for cinemas to pull it. It was the first in a series of rapid decisions from a PR team suddenly thrown into crisis-management mode.

One day they’re rolling out the red carpet, lining up interviews with celebrities and ordering crates of Champagne to promote the highly anticipated blockbuster. The next they’re forced to grapple with headlines such as:

Warner Bros. has avoided the kind of PR pitfalls committed by the National Rifle Association, which opted for tasteless tweets and weird newscasts over, god forbid, keeping a low profile. But this is uncharted territory for Hollywood. Never before has a studio been forced to grapple with a situation of this magnitude, with this sort of immediacy.

Producers swiftly cancelled The Dark Knight Rises‘ Paris premiere, where its stars were scheduled to appear on Friday night, and a day later cancelled all appearances from cast and crew at events in Mexico and Tokyo. TV networks across America pulled spots advertising the $US250 million blockbuster. Warner Bros. declared it would not announce the film’s box office figures until Monday “out of respect for the victims and their families” and every other studio followed suit, making this box office black-out a first for Hollywood. Anyone who has ever read a gushing press release about a top-performing movie will understand why.

What transpired in Colorado last Friday is far from a conventional “copycat” crime. Holmes would not have had an opportunity to see The Dark Knight Rises before his horrifying rampage and, while some have linked his actions with Heath Ledger’s character in the franchise’s previous instalment The Dark Knight, he was apparently inspired by a character created in comic books more than 70 years ago.

It is one of the movie industry’s rare off-script incidents in which the best-laid plans of studios have been derailed, marketing departments forced to walk a tightrope between social responsibility and the promotion of productions worth incredible amounts of capital. The Dark Knight grossed more than $US1 billion dollars worldwide, which provides an immediate indication of how much The Dark Knight Rises and movies of its ilk are worth.

Released nine months after the September 2001 terrorist attacks, Sony reconfigured its campaign to promote its 2002 cash cow, director Sam Raimi’s Spider-Man, which went on to collect more than $US820 million worldwide. The studio recalled posters depicting the World Trade Centre towers prominently reflected in its iconic hero’s eyes. It also pulled a trailer that included footage of a giant spider web spun between the fallen buildings. Sony maintains this footage was part of a “special shoot” and was never going to appear in the movie.

On a smaller, and certainly less-violent scale, Universal Studios generated a smattering of bad press last year when it premiered the trailer for The Dilemma, a Ron Howard-directed comedy starring Vince Vaughn and Kevin James. Gay rights groups took umbrage at a joke in which Vaughn’s character described electric cars as “gay”. The line was subsequently removed from the trailer, which was then reissued. Howard, with final-cut privilege, kept it in the movie.

In the aftermath of the Aurora killings, Warner Bros. has a far greater challenge on its hands: how to promote a marquee release it has been banking on for years that has suddenly been tarred with the most heinous of brushes. Hollywood survives not on the strength of average box office receipts but on a small number of movies that do exceptionally good business. A billion-dollar box office is potentially enough, if not to make or break a studio, than certainly to a play a factor in its structure and ongoing viability. Look no further than the financial troubles that hit MGM to be reminded of how vulnerable the Hollywood studio system can be, and why franchises such as Batman are the lifeblood.

Warner Bros. also owns Gangster Squad. It is likely to err on the side of caution and scrap the now-potentially offensive scene. If it doesn’t, it will delay the film long enough for its impact to be reduced. But how long is appropriate? How much time does a fictitious scene coincidentally connected to real-life atrocity need to “cool off” before it becomes palatable for the public? How many focus groups will pollsters with clipboards need to sit through? How will they gauge sentiment?

A dark new precedent has been set, and these are the kinds of grim questions Hollywood spinners are now forced to answer.