A U.S. Border Patrol agent on Monday works on the beach preventing migrants from entering San Diego, as seen from Tijuana, Mexico. Credit: Daniel Ochoa de Olza | AP

A Guatemalan child detained by U.S. Customs and Border Patrol died early Tuesday at a hospital in New Mexico, the agency reported.

The unidentified child is the second border-crosser to die in government custody this month. Seven-year-old Jakelin Caal died Dec. 7 of dehydration and shock, less than a day after she was apprehended by border agents.

In the second case, an agent noticed Monday that the child had become ill. The boy and his father were taken to Gerald Champion Regional Medical Center in Alamogordo, New Mexico, where the boy was diagnosed with a cold, according to a CBP news release.

Later, he was found to have a fever and was held for an additional 90 minutes before he was released with prescriptions for an antibiotic and Ibuprofen.

But the child became more seriously ill Monday night, when he vomited, and was taken back to the hospital. He died shortly after midnight on Christmas Day.

The cause of the child’s death is not known. An investigation into CBP actions will be conducted, the news release said.