A 16-year-old boy apprehended by U.S. Border Patrol was "found unresponsive" Monday morning in the facility where he was being held, according to U.S. Customs and Border Protection. A Border Patrol official said Monday afternoon that the boy, Carlos Hernandez Vásquez, died hours after a nurse at a Border Patrol station in Weslaco, Texas, determined he had the Influenza A virus.

Hernandez Vásquez was taken into custody after crossing the southern border in Texas' Rio Grande Valley on May 13, among a group of 70 people, according to the agency. He was held at a processing facility for six days before being transferred Sunday to the Border Patrol station in Weslaco, where he spent his final day.

Unaccompanied minors are typically transferred from Border Patrol to the Office of Refugee Resettlement within 72 hours. However, processing of Hernandez Vásquez's transfer did not begin until May 16. The official did not indicate what caused the delay.

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That same day, Hernandez Vásquez was allowed to call members of his family to let them know of his status, the official said.

Carlos Hernandez Vásquez CBS News

On Sunday the boy said he felt ill, according to Border Patrol, and was prescribed Tamiflu. It is not clear why he was not brought to a hospital, or how frequently he was checked on during his final hours, but the official said a wellness check was performed one hour before the boy was found unresponsive Monday morning.

Medical personnel at the facility were unable to revive him, the official said.

In a statement to CBS News, the Guatemalan consulate called for an investigation into the death. The FBI, local police, and the Department of Homeland Security Inspector General are investigating, according to the Border Patrol official.

"The Guatemalan Government regrets the death of this Guatemalan boy, presents his condolences to the family and urges that the US authorities urgently rule on the cause of death and deduct the responsibilities that merit the case," the consulate said.

Acting U.S. Customs and Border Protection Commissioner John Sanders said in a statement that the agency "is committed to the health, safety and humane treatment of those in our custody."

"The men and women of U.S. Customs and Border Protection are saddened by the tragic loss of this young man and our condolences are with his family," Sanders said. The agency said the Department of Homeland Security Office of the Inspector General has been notified, as well as the Guatemalan government, and members of Congress.

The boy is the fifth Guatemalan child to die since December after being apprehended at the U.S. border.

In the most recent instance, a 2-and-a-half-year-old who was apprehended at the U.S.-Mexico border in El Paso in April died on May 14. A Customs and Border Protection (CBP) official familiar with the case told CBS News the family encountered Border Patrol agents at Paso Del Norte Bridge on April 3. Three days later, the child was hospitalized for an unspecified illness. The family was given a notice to appear in court and was released on their own recognizance April 8.

In another recent case, a 16-year-old boy died April 30 after being apprehended by border patrol agents near El Paso on April 19. The boy, Juan de León Gutiérrez, was sent to a Brownsville, Texas, facility for unaccompanied migrant children, where staff noticed a few days later that he appeared ill. He died nine days in a hospital bed. The Guatemalan Foreign Ministry said in a statement that Gutiérrez died from complications from an infection in his brain's frontal lobe.

There were also two children's deaths in December. A 7-year-old girl, Jakelin Caal Maquin, died of a bacterial infection Dec. 8 after being in Border Patrol custody. And an 8-year-old boy, Felipe Gómez Alonzo, died on Christmas Eve.