An official at the Department of Health and Human Services is expected to tell Congress Thursday that the agency has “lost track of nearly 1,500 migrant children the agency placed with sponsors” in the U.S., according to testimony obtained by The New York Times. Steven Wagner, the acting assistant secretary of the Administration for Children and Families, will reportedly tell a Senate Homeland Security subcommittee that HHS discovered the agency lost track of the children after calling sponsors to check-in. After trying to reach 7,635 children, only 6,075 were found to have stayed with their sponsors, while 1,475 children could not be accounted for. Most of the children are reportedly from Honduras, El Salvador, and Guatemala—and were fleeing from danger south of the border. A report from two years ago found the agency failed to protect certain minors by not performing background checks and not checking in with sponsors to ensure the children were being properly cared for.