The Los Angeles Police Department plans to boost its visibility at movie theaters when "Joker" debuts next week, a move that comes amid growing concern around the release of the violent comic book drama.

The police force said there were "no credible threats" in the city, but it called on residents to be cautious and alert as the R-rated supervillain origin story hits screens.

"The Los Angeles Police Department is aware of public concerns and the historical significance associated with the premiere of the 'Joker.' While there are no credible threats in the Los Angeles area, the department will maintain high visibility around movie theaters when it opens," spokesman Josh Rubenstein said in a statement.

"We encourage everyone to go out and enjoy all of the weekend leisure activities the city has to offer," Rubenstein said, adding that locals should still "remain vigilant and always be aware of your surroundings."

"Joker," starring Joaquin Phoenix as a troubled, socially alienated stand-up comedian who descends into madness in Gotham City, made headlines this week after relatives of people killed in the 2012 shooting at a movie theater in Aurora, Colorado, sent a letter to the film's distributor, Warner Bros., expressing unease.

The Aurora shooting occurred during a midnight screening of the Batman movie "The Dark Knight Rises." The Joker character, who does not appear in the film, has long been linked with the massacre because initial press reports said the gunman told police he was the Joker. But those reports were later debunked.

"When we learned that Warner Bros. was releasing a movie ... that presents the character as a protagonist with a sympathetic origin story, it gave us pause," the five family members say in the letter, according to a copy shared by the group Guns Down America.

Critics who reviewed "Joker" after it premiered at the Venice International Film Festival last month have expressed concerns about the film's real-world implications. Indiewire critic David Ehrlich said the movie's portrait of its vengeful antihero was "profoundly dangerous," while Time critic Stephanie Zacharek wrote the character could "easily be adopted as a patron saint of incels," the online network of misogynists.

NBC News contacted more than 30 movie theater chains this week to ask if their management planned to increase security measures around the premiere of "Joker." In response, representatives for some of the chains said they could not disclose specifics about security measures.

In a statement, AMC Theatres — the largest chain in the United States — said it would enforce its existing policy banning "masks, face paint or any object that conceals the face."

"AMC does not permit weapons or items that would make other guests feel uncomfortable or detract from the moviegoing experience," company spokesman Ryan Noonan said.

Landmark Theatres, a boutique chain with 51 locations, announced a similar policy that also prohibits costumes.

Regal Cinemas, the second-largest chain in the U.S., said it was working with the National Association of Theater Owners, a prominent industry lobby group, to stay in "regular contact year-round with law enforcement."

"At Regal, we do not believe the content or the existence of any movie is a cause or a signal for violence," the company added.

The Cinemark-owned movie theater where the Aurora killings took place will not be showing "Joker," the city's police department confirmed on Twitter, adding that it would "provide enhanced security at this location."

Warner Bros., for its part, has defended the project. In a statement, the AT&T-owned studio said it believed gun violence is a major issue and extended condolences to families touched by tragedy.

"At the same time, Warner Bros. believes that one of the functions of storytelling is to provoke difficult conversations around complex issues," the studio said.

"Make no mistake: neither the fictional character Joker, nor the film, is an endorsement of real-world violence of any kind. It is not the intention of the film, the filmmakers or the studio to hold this character up as a hero," the studio added.