WASHINGTON (AP) — Authorities rescued 105 children who were forced into prostitution and arrested 150 pimps and others in a three-day law enforcement sweep in 76 American cities, the FBI said Monday. The victims, almost all girls, range in age from 13 to 17.

The largest numbers of children rescued were in San Francisco, Detroit, Milwaukee, Denver and New Orleans. The campaign, known as Operation Cross Country, was conducted under the FBI's Innocence Lost initiative.

"Child prostitution remains a persistent threat to children across the country," Ron Hosko, assistant director of the bureau's criminal investigative division, told a press conference.

The FBI said the campaign has resulted in rescuing 2,700 children since 2003.

The investigations and convictions of 1,350 have led to life imprisonment for 10 pimps and the seizure of more than $3.1 million in assets.

For the past decade, the FBI has been attacking the problem in partnership with a non-profit group, the National Center for Missing and Exploited Children.

John Ryan, the head of the center, called the problem "an escalating threat against America's children."

The Justice Department has estimated that nearly 450,000 children run away from home each year and that one-third of teens living on the street will be lured toward prostitution within 48 hours of leaving home.

Congress has introduced legislation that would require state law enforcement, foster care and child welfare programs to identify children lured into sex trafficking as victims of abuse and neglect eligible for the appropriate protections and services.

"In much of the country today if a girl is found in the custody of a so-called pimp she is not considered to be a victim of abuse, and that's just wrong and defies common sense," Sen. Ron Wyden, D-Ore., said during a Senate Finance Committee hearing last month. Wyden co-sponsored the bill with Sen. Rob Portman, R-Ohio.