LOS ANGELES (CBS) — The mass shooting in Colorado at a midnight screening of “The Dark Knight Rises” could hamper the film’s ticket sales this weekend.

The film, which is the last in a trilogy from director Christopher Nolan, was expected to open at No. 1 or No. 2 at the box office this weekend. But in the wake of the shooting, which left at least a dozen dead and dozens more wounded at a theater, movie-goers may avoid the movie and theaters altogether, KNX 1070’s Jon Baird reports.

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“I would not be surprised at all if this incident leads to an increase in security precautions at the big theater chains across the country. It’s been a concern for years,” said Matt Belloni of the Hollywood reporter.

Anyone can walk into a movie theater as long as they buy a ticket, but the shooting may lead to tougher security measures, maybe even metal detectors.

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AMC Theatres, which has 346 theatres across the United States and Canada, says they will be changing some policies with regards to films like “The Dark Knight Rises.”

“We will not allow any guests into our theatres in costumes that make other guests feel uncomfortable and we will not permit face-covering masks or fake weapons inside our buildings,” AMC Theatres said in a statement.

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The theatre chain also said they would be reinforcing their security procedures, but would not discuss any changes for safety reasons.