Landmark Theatres said it's banning costumes, masks and face paint at screenings of "Joker." The decision comes amid concerns from family members of victims in the mass shooting during a "Batman" movie in Colorado in 2012.

"Joker," which will be released on October 4, stars Joaquin Phoenix as Arthur Fleck, an aspiring stand-up comedian and clown-for-hire who becomes the classic Batman villain. Family members of the Aurora, Colorado, shooting victims said they worried the new film could prompt someone to copy the 2012 massacre.

A memo issued by the Army Criminal Investigation Command earlier this month cited concerns by the FBI and Texas law enforcement officials about a possible shooting threat to an unknown theater for the film's release, according to Stars and Stripes.

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Warner Bros., the studio that produced the movie, said in a statement that "Joker" is not an endorsement of gun violence. "We want all our guests to enjoy 'The Joker' for the cinematic achievement that it is," Landmark Theatres said on its website. "But no masks, painted faces or costumes will be permitted into our theatres."

Landmark operates 52 theaters in 27 locations, including the Landmark in Los Angeles and the Landmark in New York City.

Landmark Theatres CEO Ted Mundorff told the Hollywood Reporter that the decision to ban costumes at the film was based on a wish to make customers feel at ease.

"I want customers to be comfortable in their surroundings," Mundorff told the trade publication this week.