Demonstrators went out into the streets to protest the police violence.
Dozens of people were detained Thursday night during a mass protest against police violence in Union Square in New York City.
Demonstrators reached the City Hall building, blocking traffic in the Lower Manhattan area.
The protesters were mostly peaceful, but at one point clashes between demonstrators and police began.
Some started throwing roadblocks at the police and tried to take away their bicycles.
At least 40 people were detained.
The detainees are facing charges of assaulting the police, illegal possession of weapons and civil disobedience.