A 16-year-old migrant from Guatemala is the latest child to die while in the custody of United States immigration officials, The Associated Press reports.

Carlos Gregorio Hernandez Vasquez was apprehended and held by U.S. Customs and Border Protection (CBP) for six days before he died on Monday (May 20). He was diagnosed with the flu while in custody, but officials sent the boy to another holding facility instead of a hospital. Vasquez is reportedly the fifth migrant child to die is U.S. custody since December 2018. 

CBP released a statement on Monday regarding the boy’s death saying that he was “found unresponsive during a welfare check” at the Weslaco Border Patrol Station, where he was sent on Sunday (May 19) after spending five days at the Rio Grande Valley Sector’s Central Processing Center

John Sanders, acting commissioner for CBP, said in the official statement: “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. CBP is committed to the health, safety and humane treatment of those in our custody.”

Immigration advocates, like Efrén Olivares, a lawyer with the Texas Civil Rights Project, are demanding government protection for migrant children. “We should all be outraged and demand that those responsible for his well-being be held accountable,” Olivares told The AP. “If these were White children that were dying at this rate, people would be up in arms,” he added. “We see this callous disregard for brown, Spanish-speaking children.”

According to The AP, Vasquez was processed by U.S. immigration on May 13 as a “minor unaccompanied by a parent or legal guardian.” The organization failed to explain why Vasquez was held for six days, despite CBP guidelines that dictate that unaccompanied minors be transferred to a facility operated by the U.S. Department of Health and Human Services after three days.

A nurse practitioner diagnosed the young boy with the flu on Sunday morning, The AP reports. He was then given the medicine Tamiflu. Later that day, he was reportedly sent to Weslaco to prevent other detainees at Rio Grande from getting sick.

The Federal Bureau of Investigation and the Department of Homeland Security have launched an investigation into the teen’s death.