Nine men were arrested after a chaotic scene at a historic synagogue that saw a group of students clash with police over a secret tunnel leading into the structure from a nearby building.

The men who were arrested were protesting the tunnel being filled with concrete, the Associated Press reported. The protest turned violent when police tried to make arrests.

The group “broke through a few walls” in buildings adjacent to the Chabad-Lubvitch movement’s headquarters in New York City, spokesperson Rabbi Motti Seligson said in an email.