(CNN) The message stopped Jimmy Van Bramer dead in his tracks.
The New York City councilman says he was jogging around his Sunnyside, Queens, neighborhood last Sunday when he came upon a flyer urging American citizens to report undocumented immigrants to US Immigration and Customs Enforcement.
"It sent chills through my body because it was ominous, it was dark and it was meant to intimidate immigrants," Van Bramer said in an interview with CNN.
The flyer reads: "A notice to all citizens of the United States of America: It is your civic duty to report any and all illegal aliens to U.S. Immigration and Customs Enforcement. They have broken the law." At the bottom, it lists a contact number for ICE.
The councilman, who represents the district, says he immediately took action. In a video posted to social media, he is seen tearing down the poster which had been glued to an electrical box. Since then, several more have popped up at nearby locations.
He says the flyers have provoked fear and outrage in Queens, a richly diverse borough where nearly half of the population is foreign-born.
"What this is trying to do is turn citizens into vigilantes, encouraging them to report people to ICE without knowing whether they are documented or not," Van Bramer said. "This is a borough of immigrants, a neighborhood of immigrants and I don't want any of them, even those that are undocumented, to be afraid to walk through these streets."
While it is not clear who is responsible for putting up these flyers in Queens, the councilman says he thinks it's Vanguard America, a white supremacist group based in Texas.
Van Bramer says Vanguard America has taken credit for similar postings at college campuses in Washington state, Texas, Nebraska and Pennsylvania. CNN has tried to reach representatives from Vanguard America for comment, but they have not responded.
"Though we don't know who posted these particular signs, let's be clear. This is a racist white supremacist organization that has proudly claimed credit for creating this flyer," said Van Bramer who warned that those responsible could be subject to hefty fines. It is illegal in New York to post ads on city property.
Make the Road NY, a pro-immigrant advocacy group, also blames the anti-immigrant rhetoric and hardline policies of the Trump administration for the flyer's sudden appearance in Queens.
"The current administration's policies of intolerance and xenophobia has emboldened those who say they don't want immigrants living in this country," said Julissa Bisono, an organizer for the organization. She said Make the Road NY began a counter-messaging campaign by posting flyers around the borough with messages of support for immigrants.
Meanwhile, Van Bramer has encouraged anyone who comes across any more of these posters to take them down or report them to his office, hoping that will send a message that hate and discrimination have no place in Queens.
"We're not going to allow anyone to intimidate immigrants in this community," Van Bramer said. "We pride ourselves in being a sanctuary city and we want to make sure everyone knows that immigrants are welcome here."