Searches for retro track suits and white slip-on Vans are spiking as “Squid Game” fans hunt for Halloween costumes inspired by the wildly popular Netflix series — but the looks will not be welcome everywhere.

Principals at three New York elementary schools outside Syracuse are cracking down on “Squid Game”-related talk and play after students were mimicking the violent series at recess. Now, they’re telling parents that Halloween ensembles paying homage to the show won’t be allowed on school grounds “due to the potential violent message aligned with the costume.”

The emails were sent to parents of the roughly 1,500 students who attend Mott Road, Fayetteville and Enders Road elementary schools, Fayetteville-Manlius School District spokeswoman Nancy Cole told The Washington Post. The costume bans were first reported by WSTM.

“We have observed that some students at recess have been playing a version of [“Squid Game”] … which is intended for mature audiences, ages 16 and older,” the email from Mott Road Elementary’s principal said. “Due to concerns about the potential violent nature of the game, it is inappropriate for recess play or discussion at school.”

Store names and character names hold truth and deeper meaning in Netflix's “Squid Game.” (Allie Caren, Michelle Lee/The Washington Post)

Netflix has called reaction to the nine-episode South Korean thriller “mind-boggling.” An estimated 142 million households worldwide tuned into “Squid Game” in its first four weeks, making the series the company’s “biggest TV show ever,” an Oct. 19 letter to Netflix shareholders states.

“The breadth of Squid Game’s popularity is truly amazing,” the memo adds.

But experts are warning that the intensely popular show, which follows indebted contestants competing in deadly versions of children’s games for cash prizes, could be reaching audiences too young to handle its unsettling violence. Participants in the series play twisted versions of ordinary school games — like marbles, tug of war, and red light, green light — but losers are killed off.

"The level of violence is horrifying — more than most shows," David Anderson, the head of School and Community Programs at the New York-based Child Mind Institute, said in a blog post last week. "It's a murder fest with the premise that out of over 400 participants, there can only be one survivor."

Children should not watch “Squid Game” until their late teenage years, Anderson suggested. The Netflix series has a TV-MA rating, meaning it’s meant for mature audiences.

Fayetteville-Manlius School District Superintendent Craig Tice said in a statement to The Post that staff members recently noticed students imitating “Squid Game.”

“Because of this activity,” Tice said, “our principals wanted to make sure our families are aware that it would be inappropriate for any student to wear to school a Halloween costume from this show.”

He added that educators want families to know that some young students are talking about and mimicking aspects of “Squid Game” so parents “have the opportunity to speak with their children … and reinforce the school message that games associated with violent behavior are not appropriate for recess.”

The New York schools aren’t the first to report students imitating the hit show. Officials at Bay District Schools in Florida have also warned parents about elementary-aged students mimicking “Squid Game.”

Even if parents aren’t letting their kids watch “Squid Game,” they might still be seeing clips on gaming and video-sharing sites, the Florida district officials said, adding: “we are seeing kids trying to actually hurt each other in the name of this ‘game.’ ”

“Squid Game” Halloween costumes are among the most popular on Instagram this year. In addition to the track suits contestants wear in the games, people are searching for white numbered T-shirts like those assigned to players and the red jumpsuits and black masks guards don in the show.