(CNN) A 7-year-old Guatemalan girl died last week, hours after she was taken into Border Patrol custody, the Department of Homeland Security said.

The Washington Post first reported Thursday that the girl died of dehydration and septic shock last week in El Paso, Texas after she was taken into custody by Border Patrol after crossing illegally with her father into the United States.

"Our sincerest condolences go out to the family of the child," the Department of Homeland Security, which oversees Border Patrol, said in a statement.

"Border Patrol agents took every possible step to save the child's life under the most trying of circumstances. As fathers and mothers, brothers and sisters, we empathize with the loss of any child."

The girl and her father were part of a large group of migrants who approached Border Patrol agents in a remote area of the New Mexico desert last Thursday, the newspaper reported, citing US Customs and Border Protection records.

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