HAGATNA, Guam » The U.S. Air Force community is mourning the death of a 22-year-old senior airman from Hawaii who had been supporting Operation Christmas Drop 2015 when he collapsed following a training exercise.

The Pacific Daily News reports that the Air Force said today that Senior Airman Jeremy M. Jutba-Hake collapsed Sunday during post-flight duties at Andersen Air Force Base in Guam. He was taken to a hospital and later pronounced dead.

The cause of his death remains under investigation.

Air Force officials say Jutba-Hake had been on duty at the Guam base to support the annual Operation Christmas Drop. This year, Australian, Japanese and U.S. air force planes dropped food and toys on remote atolls in the Pacific as part of the U.S. military’s longest-running humanitarian relief mission.