A 16-year-old Guatemalan boy died in U.S. custody Monday in the Rio Grande Valley, according to a statement from Customs and Border Protection. According to a CBP official, agents found Carlos Gregorio Hernandez Vasquez unresponsive during a welfare check Monday morning after he was apprehended in Texas on May 13 in a large group of “70 other subjects.” Vasquez reportedly went through numerous medical screenings after being apprehended, but the CBP official could not definitively say he wasn’t sick upon being taken into custody. Vasquez told officers that he was not feeling well on Sunday, and an on-site nurse practitioner diagnosed him with “influenza A.” Border Patrol agents subsequently treated him with Tamiflu.

Vasquez was then transferred to the Weslaco Border Patrol Station, where officials assessed him again. However, officials found him unresponsive in a “short-term holding” room on Monday morning, and medical staff could not save his life. The Weslaco Police Department, CBP, Department of Homeland Security’s Inspector General, and the FBI are investigating the matter. The news comes after a number of Guatemalan nationals have died in U.S. custody after reaching the border. According to The New York Times, Vasquez is the fifth migrant child to have died in U.S. custody since December.