The Phoenix Police Department, in partnership with other Arizona authorities, on Friday announced 37 arrests in connection to human trafficking and sex crimes.

Undercover police placed ads on websites commonly sought out by suspects seeking illegal sex acts with children as part of an investigation dubbed Operation Broken Hearts.

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The probe targeted "sexual predators engaged in child sex crimes and human trafficking," Phoenix police wrote in a Friday Facebook post. 

Suspects "solicited and/or brokered deals for various sex acts and were subsequently arrested,"  police said.

Police told Fox News that the operation lasted a week and took place in early February. Because police were posing undercover, there were no live victims in the case. 

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Those arrested ranged from 21 to 66, according to Fox 10 Phoenix.

Also participating in the operation were the Mesa, Tempe and Chandler police departments, Homeland Security Investigations and the Attorney General's Office.

Authorities are asking anyone with information about human trafficking to contact the Human Trafficking Hotline at (888) 373-7888, or visit humantraffickinghotline.org.

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The anti-trafficking advocacy group Polaris, which operates the hotline, says that more than 63,000 human trafficking cases have been reported over the past 14 years, and the hotline has received more than 48,000 "contacts" -- emails, phone calls, texts and other forms of communication -- over the past year.