HOUSTON — A 16-year-old boy from Guatemala who died in U.S. custody Monday had been held for six days — twice as long as federal law generally permits — then transferred to another holding facility after he was diagnosed with the flu.

The teenager, identified by U.S. Customs and Border Protection as Carlos Gregorio Hernandez Vasquez, was the fifth minor from Guatemala to die after being apprehended by U.S. border agents since December.

Advocates demanded that President Donald Trump’s administration act to safeguard the lives of children in detention as border crossings surge and the U.S. Border Patrol detains thousands of families at a time in overcrowded facilities, tents, and outdoor spaces.

“We should all be outraged and demand that those responsible for his well-being be held accountable,” said Efren Olivares, a lawyer with the Texas Civil Rights Project.

“If these were white children that were dying at this rate, people would be up in arms,” he said. “We see this callous disregard for brown, Spanish-speaking children.”

John Sanders, CBP’s acting commissioner, said his agency was “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,” Sanders said.

Border Patrol agents said Carlos was apprehended on May 13 in South Texas’ Rio Grande Valley after crossing the border illegally.