An eight-year-old boy from Guatemala died in custody of the United States Customs and Border Protection on Tuesday after being detained by agents at the border between the US and Mexico, Reuters reported, citing the agency.

It is the second such death of an immigrant child this month. In the previous instance, a seven-year-old girl from Guatemala had reportedly died of dehydration and shock after being taken into custody by the Border Patrol custody.

In a statement, the Customs and Border Protection said the boy and his father were in custody on Monday when a Border Patrol agent noticed the child showing signs of illness. Both were taken to a medical centre in New Mexico’s Alamogordo, where the child was diagnosed with a common cold and fever and released.

The boy was taken back to the hospital after he started vomiting in the evening and died shortly after midnight. The father and child have not been identified and the official cause of the death is not yet known, the agency said, adding it would release more details “as available and appropriate”.

US authorities have informed Guatemalan officials of the death. Guatemala’s foreign ministry in a statement said that its consul in Phoenix, Arizona, was monitoring the situation and had sought to interview the boy’s father “to know their version of the facts”. The ministry said the boy crossed over into the US through El Paso in Texas on December 18 and was taken into custody on December 23.

“The cause of death is under investigation and medical reports have been requested to clarify the cause of death of the child,” the ministry added.

Texan Democrat Joaquin Castro, chairman-elect of the Congressional Hispanic Caucus, identified the child as Felipe Alonzo-Gomez, CNN reported. He also sought a congressional investigation into the death.

“While the Customs and Border Patrol 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 US government,” Castro said.