NEW YORK (AP) — A group of Hasidic Jewish worshippers were arrested amid a dispute over a tunnel secretly dug into the side of a historic Brooklyn synagogue,HAI Community setting off a brawl between police and those who tried to defend the makeshift passageway.

The discovery of the tunnel at the Chabad-Lubavitch world headquarters in Crown Heights prompted an emergency structural inspection from the city Tuesday.

The building at 770 Eastern Parkway was once home to the movement’s leader, Rabbi Menachem Mendel Schneerson, and draws thousands of visitors each year. Its Gothic Revival facade is immediately recognizable to adherents of the Chabad movement and replicas of the revered building have been constructed all over the world.

Motti Seligson, a spokesperson for Chabad, said a “group of extremist students” had secretly broken through the walls of a vacant building behind the headquarters, creating an underground passage beneath a row of office buildings and lecture halls that eventually connected to the synagogue.

The property’s manager brought in a construction crew Monday to fix the damaged walls, leading to a standoff with those who wanted the passageway to remain.

“Those efforts were disrupted by the extremists who broke through the wall to the synagogue, vandalizing the sanctuary, in an effort to preserve their unauthorized access,” Seligson said.

A police department spokesperson said officers were called to the building Monday afternoon to respond to a disorderly group that was trespassing and damaging a wall.

Video shot by witnesses showed police confronting young men standing within a hollowed out space inside a brick wall. After officers removed one of the men from the dusty crevasse, a group of onlookers can be seen shoving officers, tossing wooden desks and scattering prayer books. One officer appeared to deploy an irritating spray at the jeering group.

Police said 10 people were arrested for criminal mischief and criminal trespass and one for obstructing governmental administration.

It wasn’t immediately clear when the tunnel was constructed or what purpose it served.

As inspectors with the city’s building safety agency assessed the damage Tuesday, a group of police officers stood behind barricades surrounding the headquarters, blocking a line of young men from entering the building.

New York City Fire Department spokesperson Amanda Farinacci said the agency received an anonymous tip about the location last month. But when a fire prevention team responded, they found all of the exits operable and up to code, Farinacci said.

The building is now closed pending a structural safety review, Seligson said.

“This is, obviously, deeply distressing to the Lubavitch movement, and the Jewish community worldwide,” he said. “We hope and pray to be able to expeditiously restore the sanctity and decorum of this holy place.”

Schneerson led the Chabad-Lubavitch for more than four decades before his death in 1994, reinvigorating a Hasidic religious community that had been devastated by the Holocaust. The headquarters was also the epicenter of the 1991 Crown Heights riots, which began after a 7-year-old boy was struck and killed by a car in the rabbi’s motorcade.