PHOENIX — An undercover police operation targeting child sex trafficking and human trafficking in the Valley has led to the arrest of 40 people on various sex-related crimes.

Called “Operation Behind The Mask,” the undercover operation involved multiple police agencies in the Valley, including Mesa, Phoenix, Tempe, Scottsdale, FBI, HSI, and Attorney Generals Office, according to a news release from the Tempe Police Department.

Ads were posted to websites commonly used by people seeking illegal sex acts.