I suspect a high or visiting rabbi (out of parish) was tipped off to a halakha violation, and discovered the tunnel within the synagogue, which forced Rabbi Braun to take action and swiftly seal the tunnel. Given that all of these young male jews are tearing up the synagogue against the cops, it probably was the beginning of a trafficking tunnel. It's clear with the disrepair of woman's partition, the women have been discouraged to come for a very long time, so this was likely their intent.