(CNN) An 8-year-old Guatemalan boy died late Christmas Eve in the custody of US Customs and Border Protection, the agency said, the second Guatemalan child to die in the agency's custody this month.

Rep. Joaquin Castro, chairman-elect of the Congressional Hispanic Caucus, identified the child in a statement as Felipe Alonzo-Gomez.

The boy, who was detained with his father, died shortly before midnight at Gerald Champion Regional Medical Center in Alamogordo, New Mexico, about 90 miles north of the border crossing in El Paso, Texas.

"This is a tragic loss," CBP Commissioner Kevin K. McAleenan said. "On behalf of U.S. Customs and Border Protection, our deepest sympathies go out to the family."

The boy was taken to the hospital Monday after a border agent noticed signs of illness, and the medical staff first diagnosed him with a common cold and later detected a fever.

"The child was held for an additional 90 minutes for observation and then released from the hospital mid-afternoon on December 24 with prescriptions for amoxicillin and Ibuprofen," CBP said in a news release. Amoxicillin is a commonly prescribed antibiotic.

On Monday evening, the boy began vomiting and was taken back to the hospital for evaluation. He died hours later, the CBP said.

The official cause of death is unknown. CBP is conducting a review and will release more details as they become available, it said.

CBP announces policy changes in wake of death

In the wake of the boy's death, McAleenan announced a series of moves on Tuesday night.

First, Border Patrol is conducting secondary medical checks on all children in CBP care and custody with a particular focus on children under 10.

Second, Border Patrol is working with Immigration and Customs Enforcement on available surge options for transportation to Family Residential Centers and supervised release, CBP said. The agency also is reviewing other custody options to relieve capacity issues in the El Paso sector, such as working with nongovernmental organizations or local partners for temporary housing.

Third, CBP is considering options for medical assistance with other governmental partners, the agency said. That could include support from the Coast Guard, as well as possibly more aid from the Department of Defense, FEMA, Health and Human Services, and the Centers for Disease Control and Prevention.

Finally, CBP is reviewing its policies with a particular focus on the care and custody of children under 10, both at intake and beyond 24 hours in custody, the agency said.

On Tuesday, Rep. Castro offered his condolences to the boy's family and called for a congressional investigation of the death.

"While the CBP notified Congress within 24 hours as mandated by law, we must ensure that we treat migrants and asylum-seekers with human dignity and provide the necessary medical care to anyone in the custody of the United States government," he said in the statement.

Guatemala's Foreign Ministry in a statement Tuesday also asked for an investigation and access to the boy's medical records.

The ministry said CBP alerted Guatemalan officials of the death on Tuesday. The boy arrived in El Paso with his father December 18 and was transferred to the Alamogordo CBP station on Sunday, according to the statement.

"The cause of death of the minor is still being investigated and the medical records have been requested in order to help clarify the cause of death," the statement said.

Guatemala's Consul General in Phoenix, Oscar Padilla Lam, met with the boy's father in Almagordo to "hear his version of the facts," according to the statement.

The Foreign Ministry said it will provide assistance and consular protection to the father and assume responsibility for the repatriation of the boy's remains.

The CBP news release says the Department of Homeland Security is experiencing "a dramatic increase in unaccompanied children and family units arriving at our borders illegally or without authorization," and per law, holds such individuals at federal facilities until they are deported or released into the United States with a notice to appear in court.

"During their period of detention they received medical screenings and further treatment as needed," it said.

7-year-old Guatemalan girl died earlier this month

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A 7-year-old girl, Jakelin Caal Maquin, fled Guatemala with her father, and after surviving the 2,000-mile journey to New Mexico, she died December 8, fewer than 48 hours after CBP detained her and her dad.

Her body was repatriated Sunday to Guatemala, and her remains were to be transported to the indigenous community of Raxruha, where she called home.

Her death marked another flashpoint in the debate over the White House's hard-line approach to immigration enforcement, with many -- including Jakelin's family -- wondering if better medical care may have saved her.

Castro said the Trump administration's policy of turning people away from legal ports of entry -- known as "metering" -- is "putting families and children in great danger."

A congressional oversight trip last week to the CBP station where the girl and her father were detained raised "serious concerns" about facility conditions and the "lack of adequate medical supplies, equipment and resources to properly treat migrants and the agents working there," Castro said.

"Many questions remain unanswered, including how many children have died in CBP custody," Castro said.

Felipe González Morales, the UN special rapporteur on the human rights of migrants, said Monday that American authorities "must ensure that an in-depth, independent investigation" is conducted.