Two little sisters, a 5-year-old and a 3-month old, were rescued from human traffickers by undercover police in Denver as part of the FBI’s Operation Cross Country XI.

A friend of the girls’ family attempted to sell the two girls for sex to an undercover agent for $600. Such a crime seems unfathomable, but as CNN reports, these girls were just two of the 82 children rescued during the national sweep last week. 120 people were arrested.

The number of arrests may sound encouraging, but the FBI says that effort is not over.

“The average age of the victims recovered from this year’s operation is 15, the FBI said. Sellers tried to pimp them to outsiders from hotels, truck stops or online. Sometimes, sex trafficking can involve family members or family friends.”

FBI Director Christopher Wray noted, “Unfortunately, the number of traffickers arrested — and the number of children recovered — reinforces why we need to continue to do this important work. For these young children, life may never return to the way it was before.”

Underage victims were rescued across the country through coordination between local and national agencies, as well as police as far away as Thailand and the Philippines.

Holly Gibbs, a child sex trafficking survivor and patient care director of Dignity Health added, “What happened to these children is a tragedy, and they have a long journey ahead of them. But for the moment, I am glad that they are safe.”