A vigil for a Brooklyn prosecutor killed by a Williamsburg charter bus ended in chaos this weekend after activists say police attacked peaceful protesters.

A funeral vigil was held for Sarah Pitts on Friday night.

She was a prosecutor working for the Brooklyn District Attorney's Office and was killed by a bus while riding her bike earlier this month.

The vigil was organized by a group she was part of - called Riders 4 Rights. It ended in chaos and violence as protesters say police moved in on them unprovoked.

Video shows the moments protesters say they were finishing up the funeral in the park when police moved in and created a barricade in front of the group, who used their bikes to form a parallel boundary.

Members of the Cyclist Advocacy Group, who say they train in de-escalation and nonviolent protests, were telling one another not to engage with the police when they say one of the officers stepped forward and broke their line. The rest of the police then moved in towards the group.

The activists say though no one was arrested, there was nothing that prompted police to move in without warning and hitting and shoving people to the ground.