Obama-era Border Patrol Chief Mark Morgan sounded the alarm Thursday on the crisis at the southern border, testifying before Congress that the crisis is “at a magnitude never seen in modern times” and urging lawmakers to act to stop what he described as a virtual “open border policy.”

“We’re experiencing a crisis at the southern border at a magnitude never seen in modern times, it’s unprecedented,” Morgan, who served as the head of U.S. Border Patrol during the Obama administration, told the Senate Homeland Security Committee.

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Morgan made the remarks after Customs and Border Protection (CBP) said that more than 76,000 migrants were detained in February -- the highest number of apprehensions in 12 years -- and were on pace for more than 100,000 apprehensions in March. The surge in numbers has led President Trump, who declared a national emergency on the border in February, to threaten to close the southern border if Mexico did not stem the numbers flowing north, and if Congress did not act.

"If we don't make a deal with Congress...or if Mexico doesn't do what they should be doing...then we're going to close the border, that's going to be it, or we're going to close large sections of the border, maybe not all of it," he said in the Oval Office Wednesday.

Morgan told lawmakers that the difficulties the country faces at the border now are significantly worse than when he was seeking to keep numbers under control in the last administration. In particular, he pointed to the number of agents being diverted away from security to humanitarian activities.

“In 2016, as chief I estimated that 15 percent of agents' resources were being diverted from frontlines to support humanitarian activities. I saw that as a crisis and so did everyone else,” he said. "Now Border Patrol is diverting 40 percent of personnel away from frontlines to humanitarian-related functions, meanwhile cartels are exploiting the resultant resource gaps.”

Like Trump, who has blamed U.S. immigration laws in part for the crisis, Morgan said that “loopholes in our asylum laws and nonsensical judicial precedent has driven what has devolved into essentially an open border policy for a certain demographic.” He added that families coming to the border know that if they step foot on U.S. soil they can say they have "credible fear" of returning home and they'll be allowed into the U.S.

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He also warned that an unsecured border is leading to increased flows of drugs into the U.S. and called the claim that most drugs come through ports of entry “simply false.”

“We have no idea, no idea what’s coming through our southwest border,” he said.

In pushing back on certain narratives, he said that only 15 percent of migrants are found to have valid asylum claims, which he said “debunks the uniform outrage often used that immigrants are fleeing from extreme violence and persecution.”

‘We’re letting in tens of thousands of people into this country every day who we know virtually nothing about,” he said. “We must start being intellectually honest, those coming, they’re not all bad, but they’re not all good”

He urged Congress to pass laws to replace "outdated" laws on the books and gaps in Department of Homeland Security (DHS) powers, invest in further border security, support enforcement within the U.S., and he called for the U.S. to continue to work with Central American governments to increase economic opportunities.

Morgan’s comments in part echo those of former Obama-era DHS chief Jeh Johnson who said on “Cavuto LIVE” on Saturday that “by any measure, right now we have a crisis at our southern border” and cited statistics that said there were 4,000 apprehensions in just one day last week.

“That is by far a greater number than anything I saw on my watch in my three years as secretary of Homeland Security,” he said.

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Current DHS Secretary Kirstjen Nielsen was in Yuma, Arizona on Thursday to meet with leaders from Customs and Border Protection (CBP) and Immigration and Customs Enforcement (ICE) -- for a roundtable with law enforcement and local officials, as well as representatives from non-governmental organizations.

Nielsen told Fox News’ “Tucker Carlson Tonight” on Tuesday that the administration is treating the immigration crisis as a “Cat 5 hurricane disaster.”