HOUSTON (CBSDFW.COM/AP) — The federal agency that oversees the care of unaccompanied migrant children acknowledged to CBS News on Wednesday a 10-year-old girl from El Salvador died in its custody on Sept. 29, 2018.

The child’s death had not been previously reported.

She was the first of six migrant children to die in U.S. custody — or soon after being released — in the past eight months.

The U.S. Department of Health and Human Services said she died at an Omaha, Nebraska, hospital of fever and respiratory distress.

Spokesman Mark Weber said the department began caring for the unidentified girl in March 2018.

Weber said the girl was “medically fragile,” with a history of congenital heart defects.

He did not say when she entered the U.S. or whether a parent or adult accompanied her. HHS provides care to children the government considers unaccompanied.

The deaths of immigrant children in U.S. government custody have sparked calls for investigations and changes to Trump administration policy.

Weber said the department was committed to protecting the children in its custody.

(© Copyright 2019 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)