Secretary of Homeland Security Kirstjen Nielsen is headed to the U.S.-Mexico border later this week in response to the Christmas Eve death of an 8-year-old Guatemalan boy who was in the custody of U.S. Customs and Border Protection.

In a statement Wednesday, Nielsen called Felipe Gómez Alonzo death “deeply concerning” and partially blamed the influx of immigrant children detained at the border on those who oppose the Trump administration’s immigration policies.

“Our system has been pushed to a breaking point by those who seek open borders,” Nielsen said. “Smugglers, traffickers, and their own parents put these minors at risk by embarking on the dangerous and arduous journey north.”

Nielsen called on the U.S. Centers for Disease Control and Prevention, as well as “partners in Mexico,” to investigate “an uptick in sick children crossing our borders.”

She also requested that the U.S. Coast Guard medical corps assess CBP’s medical programs to find areas of improvement, and she asked the Department of Defense for more medical professionals.

Under Nielsen’s orders, all immigrant children in CBP’s custody will now receive “a more thorough hands-on assessment at the earliest possible time post-apprehension ― whether or not the accompanying adult has asked for one.”

During her trip to the border, Nielsen is scheduled to monitor medical screening procedures for detainees and observe the conditions at Border Patrol stations.

Nielsen’s requests come amid a government shutdown that has forced some Border Patrol agents and an estimated 44,000 active duty Coast Guard members to work without pay over the holiday week, the Los Angeles Times reported.

According to recent reports, CBP has seen a surge of detained immigrants who are sick. Senior administration officials told The Washington Post that “dozens” of immigrants have been taken to hospitals near the border with flu-like symptoms.

“This crisis is exacerbated by the increase in persons who are entering our custody suffering from severe respiratory illnesses or exhibit some other illness upon apprehension,” Nielsen said Wednesday. “Given the remote locations of their illegal crossing and the lack of resources, it is even more difficult for our personnel to be first responders.”

Nielsen’s announcement was issued more than a day after Alonzo, who had been detained with his father since Dec. 18, died while in CBP custody.

Alonzo is the second immigrant child to die while in detention this month. Two weeks earlier, Jakelin Caal, a 7-year-old Guatemalan girl who survived a 2,000-mile journey to the U.S., died less than 48 hours after being detained by CBP at the border, along with 163 others. Caal died of shock and dehydration, according to The Washington Post.

At the time, Nielsen blamed Caal’s family for the 7-year-old’s death, insisting that the migrant group shouldn’t have tried to enter the U.S.

“You know, this is just a very sad example of the dangers of this journey,” Nielsen said on “Fox & Friends” on Dec. 14. “This family chose to cross illegally.”

While Nielsen prepares for her border trip, House Democrats are vowing to investigate Caal’s and Alonzo’s deaths. In a statement Wednesday, House Minority Whip Steny Hoyer (D-Md.) urged the Department of Homeland Security to provide Congress with “information the public deserves to know and to take action to prevent such tragedies from recurring.”

Nielsen suggested Wednesday that the recent deaths of the two detained immigrant children were rare, pointing out that the last child to die while in custody occurred “more than a decade” ago.

“To put this in perspective, there were six migrant deaths in CBP custody during FY 2018 ― none whom were children,” Nielsen said.

“It is now clear that migrants, particularly children, are increasingly facing medical challenges and harboring illness caused by their long and dangerous journey,” she added.

But Rep. Joaquin Castro (D-Texas) challenged Nielsen’s claim that no other migrant children have died in custody in the last decade. In a tweet, Castro called on Nielsen to appear in front of Congress and say under oath that none of the six migrants who died this year under CBP custody were children.

Calling on @SecNielsen to tell Congress, under oath, that six migrant deaths occurred this fiscal year in @CBP custody, and that none were children.



In just two weeks, we heard the tragedies of #JakelinCaal & #FelipeAlonzoGomez, both under 10 years old. https://t.co/IgG3Hr4ePU — Joaquin Castro (@JoaquinCastrotx) December 26, 2018