More than 100 teenagers — many of them children from broken homes — were rescued over the weekend in a sex-trafficking crackdown that swept more than 70 cities, the FBI said Monday.

The youngest victim was 13 years old, the agency said.

The sting resulted in the arrest of 159 “pimps” from San Francisco to Miami who were involved in the commercial exploitation of both adults and children, said Ronald Hosko, assistant director of the FBI’s criminal investigative division.

It was the FBI’s largest action to date focusing on the recovery of sexually exploited children, and took law enforcement agencies to streets, motels, casinos and social media platforms, Hosko said. He said he hoped it would focus attention on sex trafficking, “this threat that robs us of our children.”

The pimps preyed in particular on troubled children, authorities said. In some of the cases, they used a popular online classified site, Backpage, to sell the children for sex, authorities said.

“From a parent’s point of view, from a law enforcement professional’s point of view, it would be enough to look through the eyes of these children and think or say, ‘Nobody cares about me,’” Hosko said.

The victims are overwhelmingly girls, and the pimps sometimes entice them with compliments or asking whether they want to make some money. The girls become trapped in a cycle that can involve drugs, physical abuse, even torture, Hosko said.

The sweep was the seventh iteration of Operation Cross Country, part of a partnership begun a decade ago by federal authorities and the National Center for Missing and Exploited Children to address child prostitution.

The sting, over three days beginning Friday, demonstrate “how many of America’s children are being sold for sex every day, many on the Internet,” said John Ryan, the center’s president and CEO.

Criminal charges against the 159 will include human trafficking, authorities said.

An estimated 240,000 children in the United States are considered at risk of sexual exploitation.

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