An illegal tunnel beneath one of the most important religious sites in New York City was about 60 feet long and 8 feet across and was not sufficiently reinforced, compromising the stability of parts of two buildings, city officials said Wednesday.

Inspectors from the Department of Buildings ordered the owners of 770 Eastern Parkway in Brooklyn, the global headquarters of the Chabad-Lubavitcher Hasidic movement, to fortify the structure and temporarily vacate parts of the buildings, and issued citations against Lubavitcher leaders who own the synagogue for two violations of work conducted without a permit.

The department also ordered a nearby two-story building on Kingston Avenue to be vacated because of fire concerns after investigators found walls had been removed.

Officials have been investigating the structural stability of the synagogue, a complex of interconnected buildings in Crown Heights often referred to simply as 770, since chaos erupted there on Monday afternoon. A group of students who wanted to maintain the rogue tunnel between 770 and at least one adjacent building protested the arrival of a cement truck that had been called in to fill the tunnel.

Some students used crowbars to try to damage a wall of a prayer space that led to the tunnel, sat in the open wall to try to prevent it from being filled and skirmished with police officers who had been called in, according to legal documents and videos from the scene.

Nine of the men were arrested at the scene on Monday evening, and five were arraigned. Two were charged with criminal mischief and obstructing governmental administration, and the other three were charged with obstructing police officers’ work. All five were released without bail. A court order prohibits them from altering or excavating beneath the Lubavitcher headquarters.