Mary Ellen Manniello, whose daughter, Courtney, 9, is a fourth grader at St. Gabriel School, a Roman Catholic elementary school in the Riverdale section of the Bronx, said she understood why officials had banned weapons with costumes.

“Kids are growing up too fast today,” she said. “They’re learning more about guns and issues in the street than educational issues.”

This year, the school has gone one step further and is prohibiting all costumes at its Halloween festivities. Ms. Manniello said it had become “a chaotic scene,” with parents helping their children change into their costumes at school.

Some parents said the no-weapons policy for Halloween costumes went too far and denied children a chance to express themselves.

“Halloween has always been the one day where it was acceptable for our children to fantasize about being somebody they are not, like a cowboy or a pirate or a person from outer space, and now we’re ripping that away from them,” said Laura Santoro, a nurse from New Milford, Conn., whose 7-year-old son, Johnny, is a second grader at Northville Elementary School there.

Ms. Santoro said that her son would dress as Capt. Jack Sparrow, the character played by Johnny Depp in the “Pirates of the Caribbean” movies, at the school’s Halloween party, but that he would not be allowed to take a sword  part of a policy that caught her by surprise last Halloween.

“I sent my son to school last year dressed as a special forces Power Ranger, and he was told that he couldn’t take along his red laser blaster, which really surprised me, because the laser is red and made of plastic and lights up, and it could never, ever be mistaken for a real gun,” Ms. Santoro said. “I mean, come on, the whole thing is getting really sad.”