Movie giant AMC Theatres says it won't be allowing people to wear costumes or face-covering masks into its theaters after a shooting in Colorado that killed at least 12 people and injured dozens more.

The Kansas City, Mo.-based company says in a statement on its website Friday that it is "terribly saddened by the random act of violence in Aurora."

The shooting happened during a a midnight showing of "The Dark Knight Rises" in the Denver suburb. A suspect was arrested outside the theater.

AMC says it is working with local law enforcement in communities across the U.S. to review its security procedures. It says on its website it has more than 300 movie houses, making it the nation's second-largest theater chain.