One Long Island child wore a Chicago Bulls jersey to school. Another wore a black T-shirt. A third played soccer with suspected gang affiliates. Law enforcement cited all three incidents as evidence that the children were members of the MS-13 gang, a civil rights organization says.

Police in Suffolk County, Long Island, have detained at least nine minors whom they claim are part of MS-13, a gang accused of a series of brutal Long Island slayings. But the teenagers—some of whom came to the U.S. fleeing gang violence in their native countries—deny being involved with gangs of any kind. Instead, the New York Civil Liberties Union says, the teens have been caught up in an overly broad crackdown on Long Island crime.

In April, two students at Bellport High School on Long Island were killed in a quadruple homicide in a nearby park. Police arrested four suspected MS-13 members in the slayings. In a Friday speech in nearby Brentwood, Long Island, President Donald Trump called on police to take a “rough” approach with suspected gang members. “Please don’t be too nice,” Trump told police, calling on officers to be more forceful when loading suspected gang members into police vehicles.

Now law enforcement has begun a crackdown on Bellport High School students suspected to be affiliated with MS-13. In interviews with nine minors who had been arrested in the gang crackdown, the NYCLU identified minors who had been “falsely labeled as gang members for wearing a black T-shirt to school, for playing soccer with suspected gang members, or for wearing clothing with the Chicago Bulls logo,” the civil rights group wrote in a letter to the Office of Refugee Resettlement.

The minors’ clothing choices were apparently interpreted as possible gang symbols.

An attorney for three of the Bellport High School students said his clients were also victims of gang violence.

“They all vehemently deny being involved in gangs,” attorney Peter Brill told the Associated Press. “They all fled their countries to get away from gang violence. This doesn’t make sense.”The allegations are particularly damaging for Brill’s three clients, all of whom are undocumented immigrants. One was sent to an immigration facility after his arrest, Brill said. Even if the minor is cleared on the gang allegations, his detention could be the start of a difficult legal battle that separates him from his family.

“We believe children are being falsely labeled as gang members and, as a result, are being hastily transported to distant high-security facilities without notice to their lawyers or family members, all in violation of a federal court order and a federal statute,” the NYCLU wrote in its letter to the Office of Refugee Resettlement (ORR).

The ORR is violated its own rules for dealing with minors, the NYCLU charged in its letter. The government agency is supposed to place minors in the least-restrictive detention facilities available, unless the ORR has determined the minor to be a threat to others. The ORR has not conducted an independent investigation into the minors, the NYCLU claims.

That means the teenagers’ detention in high-security lockups is based on police claims, which in turn are based on evidence as flimsy as a child’s choice to wear a black Tt-shirt, the NYCLU says. The ORR did not return The Daily Beast’s request for comment on Sunday.

“These practices are forcing children to fear both the gang and the government,” Irma Solis, director of the NYCLU’s Suffolk County chapter, said in a statement. “We’ve heard from children who are afraid to go to school or go outside their homes because they’re scared they will be picked up by ICE and separated from their loved ones— – and all because someone may have misunderstood a t-shirt.”Suffolk County is not the first to cast a wide dragnet for alleged gang members. In nearby New York City, police criteria for identifying gang members is vague enough to apply to any number of innocent people. The NYPD can add people to its gang member database if they meet “any two” in a list of criteria, including being spotted in a “known gang location,” having “cars/tattoos associated with gangs,” wearing “colors associated with gangs,” having “association with known gang members,” or showing “hand signs associated with gangs.” (The MS-13 gang’s best-known hand sign is virtually indistinguishable from the “rock on” devil horn sign popularized in heavy metal. The “rock on” hand sign is now a standard emoji.)

Under these criteria, a person visiting a friend in a gang, or wearing the wrong colors in a “known gang location” could risk being identified as a gang member, themselves.

That’s exactly what happened to two minors wearing the wrong Tt-shirts to school, and a third who picked the wrong soccer teammates, the NYCLU says.

“No child deserves to have his life upended or be ripped away from family based on flimsy allegations,” NYCLU Executive Director Donna Lieberman said in a statement. “Children who in many cases came to America to flee gang violence are being disappeared to face deportation without adequate protections or investigation. We will continue to challenge the recklessness of the Trump deportation machine.”