The U.S.-Mexico border has had more than half a million known "gotaways" sneak across into the U.S. since fiscal year 2022 began on October 1, Fox News has learned.

Multiple senior Department of Homeland Security sources told Fox News of the rising number of known gotaways – illegal immigrants who are spotted crossing the border but are never caught – with three months remaining in FY’22.

That number has already eclipsed the 389,155 known​ gotaways that DHS Secretary Alejandro Mayorkas previosuly testified there were in all of FY'21.

There has been an average of over 55,000 known gotaways per month​ in FY'22, according to the DHS sources.

REP. TURNER SAYS MAYORKAS ‘LYING’ ABOUT BORDER: IT'S A ‘SIGNIFICANT’ NATIONAL SECURITY THREAT

Family crossing US border

More than 500,000 known illegal immigrant gotaways have snuck across the U.S.-Mexico border without getting caught since Fiscal Year 2022 began on October 1. (AP Photo/Eugene Garcia, File)

There have been approximately 900,000​ known gotaways since the beginning of FY'21, per the sources, which is equivalent to a population bigger than the city of San Francisco sneaking across the border without apprehension. 

The surging numbers at the border come after the Biden administration has repeatedly claimed the border is "closed," "secure" and under "operational control."

After Mayorkas spoke at the Aspen Security Forum on Tuesday and dismissed claims about the border not being secure, multiple border agents pushed back against the administration as they face the overwhelming migrant crisis on the front lines.

Mayorkas testifies before Congress

U.S. Secretary of Homeland Security Alejandro Mayorkas has dismissed claims that the U.S. border is not secure. (Kevin Dietsch/Getty Images, File)

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"Hundreds of thousands crossing every month is not the definition of secure," one agent told Fox News Digital last week. "They are liars and anyone who believes them are fools."

Fox News’ Adam Shaw and Peter Hasson contributed to this report.