Somber ceremonies at New York’s Ground Zero to mark the recent ninth anniversary of the September 11th attacks were overshadowed by large demonstrations both for and against the construction of an Islamic community center and mosque to be located two blocks away on Park Place.

The larger of the two rallies, organized by Pamela Geller, the conservative blogger credited with initially calling attention to the proposed Islamic Center in Lower Manhattan, took place steps away from Ground Zero last Saturday. Speakers at the rally, including former United Nations ambassador John Bolton, media provocateur Andrew Breitbart and anti-Islamic Dutch politician Geert Wilders, assailed the project as an affront to the memory of those who were killed in 2001.

But beyond its shared opposition to the Islamic Center, the crowd was marked by ideological diversity. Some sported Tea Party-related insignia; others made clear that they were motivated to attend by their Christian faith. Many clutched American flags and photos of loved ones who perished in the attacks. In short, it was a perfect recipe for impassioned debate, emotional tirades and—as we witnessed—disturbing outbursts.

At one point, a young woman wearing a headscarf was accosted by the crowd after her friend blew a vuvuzela—the noise-making device of World Cup infamy. As evidenced by video recorded at the event, some of the surrounding rally-goers became instantly incensed, shouting anti-Muslim epithets and ripping the hijab from her head. Her friend also reported being spat on.

Though sincere in their sentiments, these protesters cast a dark shadow over what should have been a day of remembrance and reflection.