HOWARD COUNTY, MD — This is no joke. Landmark Theaters, a Los Angeles-based chain with screens across the country, will ban moviegoers from wearing masks, painted faces or costumes to screenings of the upcoming "Joker" film.

The move comes in response to growing concerns about the violence depicted in the film and after worries expressed by the families of those killed in a 2012 mass shooting at a Colorado theater screening of an earlier Batman film. Separately, AMC Theatres, the biggest movie-theater chain in the United States, previously banned masks in theaters after the Colorado mass shooting, but the company issued a reminder last week that audience members are not allowed to wear anything that obscures their faces. Costumes are still permitted.

"Guests are welcome to come dressed in costume, but we do not permit masks, face paint or any object that conceals the face," AMC said in a widely reported statement. "AMC does not permit weapons or items that would make other guests feel uncomfortable or detract from the movie going experience." "Joker" was released Friday.

Howard County has one of the popular AMC Theatres in it. AMC Columbia 14: 10300 Little Patuxent Pkwy., Columbia

The film stars Joaquin Phoenix as a failed clown who unravels into darkness and fights back against society. The movie has been criticized for glorifying mass violence, and Phoenix recently walked out of an interview after being asked whether the film could inspire real violence.

In the weeks before the film's opening date, the FBI told local law-enforcement agencies across the country to watch for troubling online posts, according to the Washington Post.