The surge of unaccompanied children pouring across the Mexico border has spiked in recent months, putting the kids in danger and jeopardizing the safety of U.S. citizens, a powerful lawmaker told the Department of Homeland Security in a blistering letter earlier this week.

The Obama administration is not taking the matter of “shocking” and “alarming” increases in the number of children flooding in seriously, Sen. Ron Johnson, R-Wis., wrote in the letter to DHS Secretary Jeh Johnson. The lawmaker said the crisis has only worsened since it gained national prominence two years ago, with nearly 6,000 unaccompanied children and more than 9,000 families from Central America apprehended by U.S. Border Patrol last month, Johnson, who chairs the Senate Committee on Homeland Security and Governmental Affairs, said.

“Over the last several years, the United States has experienced a surge of illegal immigrants entering the country through our porous southwest border,” Johnson wrote in the September 20 letter. “Since 2014, over 100,000 unaccompanied children and a similar number of family units have arrived at our border. I am concerned the surge appears to be spiking in recent months, with the number of people apprehended doubling and even tripling from the same months in previous years.”

Department of Homeland Security statistics show that in July, its U.S. Customs and Border Protection agency apprehended 5,068 unaccompanied children, compared with 4,182 in 2015, a 21 percent increase, and they took in 7,574 families this year compared with 4,503 families in 2015, a 68 percent increase.

This current flood of illegal Central American migrants making the perilous journey to America is on par with the inundation Border Patrol contended with in 2014, Johnson said. But the Obama administration is not taking the current emergency “seriously,” Johnson added.

As a result, many children sent by their families to cross the border alone and make their way in the United States are finding themselves in treacherous predicaments, Johnson said.

“Specifically, unaccompanied children have been forced to work in unsafe conditions, miss school and become the victims of sexual predators after being dispersed by the U.S. government throughout the country,” Johnson said.

The reason the illegal immigrant apprehension numbers from Central America are going up: They know they are not getting detained, or removed and that is encouragement for them to keep coming, said Claude Arnold is a retired U.S. Immigration and Customs Enforcement special agent in charge of Homeland Security Investigations.

“When we don’t detain people, and don’t remove people, it encourages more people to come,” Arnold said. “It does not take long to get back to populations inclined to cross illegally into the U.S. that this is happening.”

The spike in new illegal arrivals from Central America alarming, said Jessica Vaughan, director of policy studies for the Washington-DC based Center on Immigration Studies, and can create a host of problems for Americans.

“Unfortunately it is not working out well in the American communities where they are resettled, which have had to cope with the social and public safety strains that have resulted, particularly in the schools,” Vaughan said.

Most concerning, Vaughan said, is that law enforcement agencies have noted a significant increase in violent gang crime activity that is in many cases attributable to gang members allowed in as part of this influx.

Further, the administration’s emphasis on speed in processing the unaccompanied children, as opposed to taking care to make sure the kids are placed in an appropriate and safe environment, has resulted in a litany of child abuse and trafficking cases, Vaughan said.

"The Obama administration’s handling of this phenomenon has been disastrous for some of the migrants, and most definitely problematic and costly for the communities where they have been resettled,” Vaughan said.

DHS could not immediately be reached for comment, but the U.S. Department of Homeland Security director has been asked to provide Johnson’s committee with the most recent Southwest Border Threat Assessment, all DHS policies, memorandums and directives related to the release of apprehension data, and a plan to address the “worsening” crisis at the U.S. border by Sept. 26.