>>> rescue of more than 100 children, part of a nationwide sting operation into child sex trafficking and they also announced about 150 alleged traffickers are under arrest tonight. officials say the children are among those often referred to as lost kids who drop out of sight with no one to look out for them. our justice correspondent pete williams has the story tonight.

>> reporter: in a weekend operation carried out by the fbi and hundreds of local police nationwide, officials say they freed 105 children trapped into child prostitution and arrested 150 adults who will face a range of charges, including human trafficking . investigators say the enforcement operation focused on places where young teenaged girls were made available for sex.

>> that includes tracks, truck stops, motels, casinos, internet sites , social media platforms and the like.

>> reporter: it's the latest stage in what the fbi calls operation cross-country carried out this time in 76 cities, bringing to 2,700 the number of children rescued from child predators in the past decade.

>> may i speak with lauren.

>> reporter: agents posed as potential customers responding to online ads and arranging to meet girls in hotel rooms where they were then rescued and taken to a safe place for victim assistance.

>> the traffickers are preying on youth with low self-esteem and minimum social support which is why there's this connection to welfare and youth runaway and homeless youth .

>> reporter: some of the victims, girls ages 13 to 17, were lured from foster or group homes or were living at home, already victims of abuse, and those who prey on them know where to find them.

>> they are coming from the malls in addition to schools. some of these predators know what to look for. they know the signs and symptoms of these young girls who may be isolated from a peer network or having problems

>> reporter: adults who exploit them can face tough punishment. some get 15 years in prison. a dozen or so have been sentenced to life. pete williams , nbc news at the fbi in washington.