What often happens at such events is that hard-liners--those who glorify violence--often deliberately mingle among large masses of peaceful protesters, in order to convey the false impression that everyone else in the crowd shares their lust for violence. They actually seek to provoke a brutal response from law enforcement, since it serves their cause by radicalizing others.

I saw this often during demonstrations I attended in DC against the Vietnam War. In this way, it may APPEAR that those calling for a ceasefire in Gaza are all promoting the virulently antisemitic Hamas agenda, while only a small number, scattered through the crowd, actually brandish these slogans and banners.