U.S. AIR FORCE ACADEMY, Colo. (KXRM) — The parents of a 21-year-old cadet who died at the U.S. Air Force Academy in January told Military.com that the preliminary reports indicate he may have died due to a blocked artery in his lungs.

Cadet 3rd Class Hunter Brown died on Jan. 9 after suffering a medical emergency on his way to class. USAFA said Brown was leaving his dormitory that morning when the emergency occurred, and academy first responders were immediately called. First responders provided life-saving measures but were ultimately unsuccessful.

Brown’s parents spoke with Military.com, and said their son had been recovering from a foot surgery he’d undergone two months prior to repair a ligament he’d torn during football practice as an offensive lineman for the Air Force Falcons football team.

“What happened was a total shock,” Brown’s mother, Candyce, told Military.com. “He was doing well with his recovery.”

Brown’s parents also told Military.com that preliminary reports point to his cause of death being a pulmonary embolism, or a blocked artery in his lungs. Officials said there was a blood clot in his uninjured leg that was likely to blame. The final autopsy is pending toxicology reports.

Military.com said Brown’s parents want people to know that their son was protective of his younger sister, was a diligent student who was fluent in French, and was a loyal teammate to his fellow Air Force Academy cadets.

“To know Hunter was to love Hunter,” his father said. “He didn’t meet a stranger, he was friendly to everybody. He could be serious and he could joke, and he knew the difference and when to do both.”