(CBS) — Several hundred people rallied and marched in downtown Chicago Saturday during an annual event called Slut Walk Chicago.

Some of the mostly women in the crowd went topless with some well-placed x’s on their breasts made of duct tape.

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The event is part of an international “Slut Walk” movement.

It started several years ago after a police officer in Canada told some college students that woman should avoid dressing like sluts in order not to be victimized. His words sparked outrage.

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The women who organized the local event say they’re fighting what they call rape culture and supporting victims of sexual assault.

“The idea that acts of violence can be excused due to a victim’s dress, state of intoxication, location and sexual history is absolutely ridiculous and feeds into a cultural view of sexual assault as not a real crime,” said organizer Liz Sheridan.

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After the rally, they marched through the streets chanting, “Whatever we wear, wherever we go, yes means yes, no means no.”