SACRAMENTO (AP) — Federal, state and local authorities in California have made more than three dozen arrests and recovered 27 juveniles as part of an annual national crackdown on child sex trafficking.

FBI officials announced the results of last week’s national roundup on Monday as they try to draw attention to what they describe as a pervasive problem. They also say many people don’t recognize it as an issue in the U.S.

Agents urged parents to monitor their children’s social media accounts as a way of thwarting predators.

The Sacramento-based FBI region made seven arrests and recovered nine juveniles. There were 13 arrests and six recoveries in the San Francisco region.

In Southern California, there 12 arrests and 10 recoveries in Los Angeles, and six arrests and two recoveries in San Diego.