DENVER (AP) — FBI officials in Denver rescued more juveniles as part of a nationwide crackdown on child sex trafficking than any other FBI division office.

FBI officials said Monday they recovered 18 of 168 juveniles as part of the annual initiative known as Operation Cross Country. As part of the same effort authorities also arrested 281 pimps, 11 of whom were in Denver.

The FBI says the rescues and arrests took place in 106 cities as part of an initiative targeting truck stops, casinos and websites that advertise escorts and sex for sale. Officials say many of the young victims had never been reported missing.

This is the eighth such week long-operation. The FBI says nearly 3,600 children have so far been recovered from the streets.