CBS2's Dick Brennan reports two groups of protesters occasionally clashed with officers as they were enforcing the 8 p.m. curfew.
Some say the protesters were trying to get over the bridges but were ultimately turned away.
Police say dozens of arrests were made on both sides of the bridges.
Public Advocate Jumaane Williams says he saw police being very aggressive towards peaceful protesters.
He says they were yelling "mayor's curfew" and using force, pushing protesters back unnecessarily.
"People were literally nonviolently protesting in the street and they started getting whaled on. When I first came up, when they came off of the bridge, I came up and we were walking toward them and I see the aggression. I came up and I asked, 'What happened? Just tell me what happened.' 'You know what happened, you know what happened,'" Williams said.
Williams says some protesters were injured, but he says he didn't have exact numbers of the cause of the injuries.
The NYPD said they're investigating the incidents at the two bridges.
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