It was just three weeks ago that the 16-year-old was detained by immigration agents in Texas after traveling with his father to the United States. The father was deported back to Guatemala. The child was sent to New York.

Today, he sits in a children’s residence, one of an estimated 700 young people who have been placed with child care agencies in New York since President Trump announced his “zero tolerance” policy of separating children from family members when they are apprehended at the southern border.

Amid a rising outcry over the practice, and even as the president signed an executive order ending it, Gov. Andrew M. Cuomo toured one of the agency campuses with a New York Times reporter for a rare glimpse of these children’s lives. Because the agency that runs the residence receives federal funding that could be imperiled by speaking to the press, it offered the tour on the condition that its name, exact location and the name of the children interviewed not be disclosed.

Mr. Cuomo said that he wanted to visit the residence to make sure that the children there were being well cared for, and he excoriated the Trump administration for not informing him of the presence of the separated children in New York earlier. “They’re placing children in state-certified facilities, state-regulated facilities, and not even communicating with us,” he said.