The Landmark Theaters chain will ban costumes and masks for moviegoers during screenings of the film "Joker," the theater company said on Thursday, following concerns expressed by families involved in a 2012 mass shooting during a Batman film in Aurora, Colorado.

The Los Angeles-based chain, which runs 52 theaters in 27 markets, said it wanted customers to enjoy the film set to open October 4 as a "cinematic achievement." However "no masks, painted faces or costumes will be permitted into our theaters," read the statement to Reuters.

Landmark joins the nation's largest movie chain, Kansas-based AMC Theatres, which has banned masks in theaters since the Colorado massacre that killed a dozen and wounded scores of others, and re-affirmed that ban.

AMC, which runs more than 650 cinemas, reminded customers this week that while it allowed costumes, it did not allow masks.

"Guests are welcome to come dressed in costume, but we do not permit masks, face paint or any object that conceals the face," it said in a statement.

Landmark did not give a reason for its ban.

The move comes after families of some of the victims of the shooting sent a letter to Warner Bros., the studio behind the  "Joker, " expressing concern.

Some of those at the midnight screening in the packed Aurora theater had been wearing costumes. The mass shooting at the Century 16 Theater multiplex owned by Cinemark USA Inc. killed 12 and wounded 70.

The gunman, James Holmes, is serving multiple life sentences after being convicted of mass murder, despite pleading not guilty by reason of insanity.

The new film depicts the mental breakdown of the Joker character, the nemesis of Batman in various movie, television and comic book adaptations, that leads to violence.

The families' letter also urged Warner Bros. to end political contributions to candidates who take money from the National Rifle Association and to fund gun violence intervention programs.

In response, Warner Bros. issued a statement of sympathy for the victims and their families, Entertainment Weekly reported.

"Our company has a long history of donating to victims of violence, including Aurora, and in recent weeks, our parent company joined other business leaders to call on policymakers to enact bipartisan legislation to address this epidemic," read the Warner Bros. statement.

But the movie does not endorse real-world violence and does not hold up the Batman villain as a hero, it added.

Los Angeles police aim to step up visibility during the film's opening weekend.

"The Los Angeles Police Department is aware of public concerns and the historical significance associated with the premiere of the Joker," it said in a statement to Reuters.

Aurora police have said Cinemark will not screen "Joker" at the Colorado multiplex, where they continue to provide enhanced security.

"We recognize this release may cause concern for the families, friends, first responders and beyond," police said in a statement on Wednesday.