(HOUSTON) — The U.S. government says a 16-year-old Guatemalan died Monday at a Border Patrol station in South Texas, the fifth death of a migrant child since December.

U.S. Customs and Border Protection said in a statement that Border Patrol apprehended the teenager in South Texas’ Rio Grande Valley on May 13. The agency says the teenager was found unresponsive Monday morning during a welfare check at the agency’s Weslaco, Texas, station. The cause of death is unknown.

The agency did not say why the teenager had been detained for a week, but said he was “due for placement” in a facility for youth operated by the U.S. Department of Health and Human Services.

Federal law requires the Department of Homeland Security to send minors unaccompanied by a parent or legal guardian to HHS within 72 hours of determining that the child is unaccompanied.