News of a brawl between police and worshippers on Monday over a secret underground tunnel found connected to a historic Brooklyn synagogue was picked up quickly on social media, with posts spreading baseless claims about the passage, many laced with antisemitism.

The conflict at the Chabad Lubavitch World Headquarters in New York City, which serves as the center of an influential Hasidic Jewish movement, began when a cement truck arrived to seal the tunnel’s opening. Proponents of the tunnel then staged a protest and ripped off the wooden siding of the synagogue. Police called to the scene ultimately arrested nine people.

Those supporting the tunnel said they were carrying out an “expansion” plan long envisioned by the former head of the movement, Rabbi Menachem Mendel Schneerson. But that hasn’t stopped a proliferation of social media posts falsely suggesting the passage is proof of illicit activities such as child sex trafficking.

Here’s a closer look at the facts.

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CLAIM: The tunnel is connected to a local children’s museum.

THE FACTS: The tunnel does not connect to the Jewish Children’s Museum, which is located across the street from Chabad’s headquarters.

Commonly referred to as 770, a nod to the address of the complex’s original building, the Chabad headquarters now encompasses multiple adjacent structures in the Crown Heights section of Brooklyn.

The passageway is believed to have started in the basement of an empty apartment building behind the headquarters, snaking under a series of offices and lecture halls before eventually connecting to the synagogue, Motti Seligson, a spokesperson for Chabad, told The Associated Press.

A building at 770 Eastern Parkway was purchased in 1940, the first of what would become the Chabad complex. Its upper floors served as a home for Chabad’s Sixth Rebbe, or spiritual leader, while the first floor housed offices and a main synagogue for the movement, according to Chabad’s website.

Starting in the 1960s, the headquarters expanded into an apartment building next door, at 784-788 Eastern Parkway. The main synagogue, where Monday’s brawl took place, was moved from the original building to the basement of this structure. A smaller synagogue remains in use at 770 Eastern Parkway. Another building, on the original structure’s west side at 760 Eastern Parkway, is now a Chabad library.

The complex is a deeply revered Jewish site, especially within the Chabad movement. It receives thousands of visitors each year, including international students and religious leaders.

The Jewish Children’s Museum can be found on the corner directly to the east of Chabad’s headquarters, across Kingston Avenue at 792 Eastern Parkway. It began as an exposition at the Jacob Javits Convention Center in New York City in 1986 and opened as a permanent museum in 2004.

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CLAIM: The tunnel was used for child sex trafficking or other illicit activities.

THE FACTS: Such claims are unfounded, hinting at long-standing antisemitic tropes and more recent baseless conspiracy theories about child trafficking rings run by elite public figures, including government officials.

The exact purpose and provenance of the tunnel remains the subject of some debate, but there is no credible evidence it was used for the nefarious purposes social media users are falsely connecting it to.

Officials and locals said young men in the Chabad community recently built the passage to the sanctuary in secret.

Seligson, the Chabad spokesperson, characterized the construction as a rogue act of vandalism committed by a group of misguided young men, calling them “extremists” who were attempting to “preserve their unauthorized access” to the synagogue. Those who supported the tunnel, however, said they were carrying out an “expansion” plan long envisioned by Schneerson, the former head of the Chabad movement.

Also known as the Seventh Rebbe, Schneerson led the Chabad-Lubavitch movement for more than four decades before his death in 1994, reinvigorating a Hasidic religious community that had been devastated by the Holocaust.

Many supporters of the expansion believe Schneerson is still alive and that he is the Messiah. This idea is largely rejected by Chabad and has created a schism within the movement.

Chabad leaders declined to say when they discovered the tunnel. But several worshippers said word of its existence had spread through the community in recent weeks.

Asked for comment regarding the claims of sex trafficking or other illicit activities, the NYPD sent the AP a list of the charges issued in the case.

Nine people were arrested as a result of the brawl at Chabad’s headquarters. They were charged with crimes including criminal mischief, reckless endangerment, and obstructing governmental administration, according to police. Another three received summonses for disorderly conduct.

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This is part of AP’s effort to address widely shared misinformation, including work with outside companies and organizations to add factual context to misleading content that is circulating online. Learn more about fact-checking at AP.