The F.B.I. led a five day operation meant to discover child prostitution networks and managed to save 21 sexually exploited children, officials announced Wednesday. The sweep was coordinated by the Crimes Against Children Unit of the F.B.I.

According to The New York Times, authorities said that the operation was the biggest of this kind, ending with the arrest of 389 people involved in trafficking children for prostitution. 16 cities nationwide have been raided over the past five days and the sweep involved local, state and federal agencies which helped with the rescuing of the children. Many of them had run away from home and were lured into this way of life.

 “A lot of times the individuals come from broken homes. They’ve been out there for years. The subculture brought them in, trained them and made them believe there’s nothing else,” said Sandra Berchtold, the spokeswoman for the Detroit F.B.I, reported The New York Times.

The sweep marked the fifth anniversary of the Innocence Lost National Initiative, which has led to the conviction of 308 people and to the rescuing of 433 exploited children. Even if these kind of operations are successful, the factor which is raising more problems is the Internet.

Robert S. Mueller III, the F.B.I. director, said that the advanced technology facilitates “these criminal enterprises.”

A study made by the University of Pennsylvania revealed that about 300,000 children in the United States risked being exploited for commercial uses, reported The Associated Press.

The raided cities were: Los Angeles, Sacramento and Oakland, California; Las Vegas and Reno, Nevada; Phoenix, Arizona; Houston and Dallas, Texas; Detroit, Michigan; Toledo, Ohio; Boston, Massachusetts; Washington; Montgomery County, Maryland; Atlanta, Georgia; and Miami and Tampa, Florida.