FBI Director Christopher Wray on Thursday said there is "no question" that cartel activity from Mexico is "spilling over" into the U.S. – as the country faces a historic crisis at the southern border triggered by a massive surge in migration.

Wray was asked at a House Judiciary Committee hearing by Rep. Tom McClintock, R-Calif., whether his agency knew of instances where foreign nationals coming across the border were deeply indebted to cartels and smugglers.

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June 10, 2021: Federal Bureau of Investigation (FBI) Director Christopher Wray testifies before the House Judiciary Committee oversight hearing on the Federal Bureau of Investigation on Capitol Hill in Washington. (AP Photo/Manuel Balce Ceneta)

"Certainly, we have seen quite a number of such instances, absolutely," Wray said.

McClintock followed up and asked if those debts are collected through indentured servitude to the cartels.

"In some cases, definitely," the FBI director responded. ‘We are pursuing a number of human trafficking task forces, as well as working on certain taskforces with DHS [Department of Homeland Security] to try to address that issue."

"But there’s no question that the cartel activity on the other side of the border is spilling over in all sorts of ways and you just put your finger on one that is extremely concerning," he added.

The Biden administration is faced with the challenge of a massive spike in migration across the southern border, with more than 180,000 migrants encountered in May alone. That’s compared to just over 23,000 in May last year, and the third month in a row it has surpassed the highest number of encounters (144,000) during the 2019 border crisis.

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Many of those coming to the border are using cartels to smuggle either themselves or their children into the country. They are often taken first to stash houses and then deeper into the interior by smugglers who know how to navigate the treacherous border environment.

But officials have warned that those brought into the country are often in debt to smugglers, who charge exorbitant fees to poor migrants. Additionally, gang members and convicted sex offenders have attempted to take advantage of the migrant wave by trying to sneak in past overwhelmed agents on the ground.

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Meanwhile, smugglers have been dumping unaccompanied kids at the border as young as 3 years old and leaving them alone for Border Patrol agents to find and rescue – knowing that officials will then reunite the children with their parents, who are often already in the country.