PHOENIX - The ACLU filed a class-action lawsuit against the City of Phoenix, Police Chief Jeri Williams and some Phoenix police officers.

The lawsuit alleges they violated the rights of thousands of peaceful anti-Trump protesters who were gathered during and after a rally the president was holding in downtown Phoenix at the Phoenix Convention Center.

The protests started out peacefully in downtown Phoenix, but ended with tear gas, pepper spray and overheated protestors rallying against President Donald Trump.

The ACLU says "Phoenix police officers ended the peaceful protest when they began attacking protesters with heavy weaponry," and "many Arizonans went home from the protest with physical and emotional trauma because of police actions."

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Phoenix PD released an internal report earlier this year detailing officers' actions that night. The final conclusion from that report was that no misconduct was found. Phoenix Police Chief Jeri Williams admitted lessons were learned and spoke with 12 News several months ago about that night.

"So there were a small group of people,15-20, who made the conscious decision and when I say conscious decision, they came with backpacks filled with gas masks, things to cover their faces, different things to throw at officers," Chief Williams said. "They planned to create havoc and to create some nuances."

12 News reached out to Phoenix PD for comment on the lawsuit via email and a spokesperson responded saying, "Due to pending litigation we are precluded from speaking about the lawsuit."

The ACLU says plaintiffs want the court to stop Phoenix police from using excessive force against protesters and are seeking financial damages for anyone whose First Amendment rights were violated that night.