Border Patrol agents in one part of the southern border arrested three child sex offenders within two days, the agency announced this week -- leading the sector’s union to ask "how many others got through?"

Customs and Border Protection says that on Jan. 30 agents stopped two illegal immigrants attempting to slip past them. One of them is a 40-year-old Salvadoran national with a prior conviction of unlawful sexual activity with a minor in Salt Lake City, Utah from 2008. He had most recently been deported last year, the agency said.

The next day, agents nabbed another Salvadoran national with prior convictions in Washington for rape and sexual assault of a child. He had been deported in 2018 after being sentenced to 18 months in jail.

The same day, agents found a Mexican national as part of a group of eight illegal immigrants attempting to evade Border Patrol. The man had been convicted in 2016 in Florida of lewd or lascivious acts with a child. He had been deported in 2021.

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Horseback border patrol agent

A Border Patrol agent on horseback monitors the area near where the U.S.-Mexico border fence meets the Pacific Ocean on Nov. 7, 2021. (Frederic J. Brown/AFP via Getty Images)

The agency noted that they all face a potential charge of re-entry after deportation, which carries up to a 20-year prison sentence.

The captures come amid ongoing concerns about the number of "gotaways" -- illegal immigrants who evade Border Patrol but are observed on alternative forms of surveillance -- getting into the U.S. amid an overwhelming migrant crisis facing agents.

Sources told Fox News that there have been over 300,000 "gotaways" this fiscal year, which began in October.

In fiscal year 2022, there were nearly 600,000 gotaways. There were 389,155 gotaways at the border in fiscal 2021, and fiscal 2023 is on track to easily outpace those numbers. Last month, agents told Fox News there have been more than 1.2 million gotaways during the Biden administration.

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Tom Homan, a former acting Immigration and Customs Enforcement (ICE) director, told Fox News the number should "scare the hell out of every American" and said there was a reason these migrants are not turning themselves in to Border Patrol to be processed and released into the U.S.

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"Why would they not take advantage of the program? Because they don't want to be fingerprinted, and there's a reason for that," he said.

Those concerns were echoed on Thursday by the Del Rio branch of the National Border Patrol Council.

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"Over 1 million people got away while agents were indoors processing over the past 2 years - how many others got through?" the branch asked.

Fox News' Griff Jenkins contributed to this report.