EXCLUSIVE: Reps. August Pfluger, R-Texas, and Mayra Flores, R-Texas, are calling for the House Homeland Security Committee to hold a hearing on the number of known or suspected terrorists encountered at the southern border -- amid ongoing Republican concerns about who might be getting into the country.

In a letter to Chairman Bennie Thompson, the two lawmakers cite the recent case of Isnardo Garcia-Amando, who was on the Terrorist Screening Database (TSDB) but was released into the country with an ankle bracelet. He was not arrested until two weeks after his name was flagged by the FBI.

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They also note the arrest of Shihab Ahmed Shihab who, according to the Department of Justice, exchanged money with other individuals in an attempt to smuggle four Iraqi nationals into the United States across the southern border to help kill former President George W. Bush.

"These recent stories are unsurprising given the ever-growing security risks at our southern border," the lawmakers say.

Fox News reported in June that, so far this fiscal year (FY), U.S. Border Patrol has arrested 50 migrants on the TSDB at the southern border between ports of entry.

That is compared to 15 in FY21, which was up from three in FY20 and zero in FY19. There were six in FY18 and two in FY17 -- meaning that the numbers this year are already higher than the previous five years combined.

The TSDB contains the information of those "known or reasonably suspected of being involved in terrorist activities" and the numbers of those encountered between ports of entry by Border Patrol has been on the rise. 

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At the northern and southern borders' ports of entry, there have been a total of 192 encounters (142 at the northern border and 50 at the southern border) by CBP’s Office of Field Operations. That is compared to 157 in FY21, 196 in FY 20, 538 in FY19, 351 in FY 18 and 333 in FY17.

They also note Fox’s reporting that there have been 440,000 known "gotaways" since October alone -- and ask "how many watchlisted individuals are possibly getting away?"

Noting that it only took 19 terrorists to commit the 9/11 terror attacks, they say: "We have been successful in warding off an attack of that magnitude up until now, but these increased encounters on our borders are indicative of a greater threat to come."

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"In the wake of 9/11, the nation was told by former director George Tenet that ‘the system was blinking red.’ We cannot place ourselves in a similar situation," they write. "It is imperative that we hold a hearing to understand the full scope of this threat and take action to prevent any harm from coming to our homeland."

Pfluger has been one of a number of Republicans pushing for the Department of Homeland Security to reveal the number of encounters on the TSDB. Customs and Border Protection (CBP) began making that number public in May.

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Flores, meanwhile, turned a Texas House seat red in a special election last month after Rep. Filemon Vela, who held the seat for nearly 10 years, resigned in March and vacated the seat. 

Flores is now the first Mexican-born congresswoman to serve in the House. Her family moved to the United States when she was 6 years old.

Fox News' Bill Melugin contributed to this report.