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Thousands of protesters marched across the country on Saturday, Dec. 13, to demonstrate against police tactics used on black men.

Millions March NYC was a call for justice for Mike Brown, Eric Garner, Akai Gurley and other victims of police brutality. CBS News reports that at least 25,000 gathered in Washington Square Park and thousands of people rallied outside NYPD headquarters.

"#MillionsMarchNYC" quickly took over Twitter as pictures and video of the event were shared from protesters, and some celebs also shared what they were seeing.

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Oscar-winning actress Lupita Nyong'o shared an Instagram collage from the event with the caption, "Solidarity. #blacklivesmatter #millionsmarchnyc."

Several members of "Orange Is the New Black" were also a part of the march. Actress Vicky Jeudy posted a photo of the group holding "I Can't Breathe" signs and doing the "Hands Up, Don't Shoot" gesture.

Protesters also carried signs that read "Hands Up. Don't Shoot" and "Black Lives Matter."

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"Mistresses" actress Alyssa Milano retweeted a time-lapse video that has gone viral since Dec. 13, and you can see the scene from a window overlooking 6th Avenue and 29th Street in just 28 seconds.