The bout was over and Polish referee Mageja Dziurgota called 18-year-old Croatian boxer Vido Loncar to the center of the ring.
Dziurgota had just stopped the light-heavyweight fight between Loncar and Lithuanian Algirdas Baniulis at the European Youth Boxing Championships in Zagreb, Croatia, on Monday.
After the referee explained his decision to Loncar, the Telegraph said, the Croatian boxer suddenly punched Dziurgota in the face, knocking him to the canvas.
As opponent Baniulis quickly got himself through the ropes and away from the attack, Loncar continued pummeling the ref until the boxer was pulled by his leg out of the ring.
After the smoke cleared, Dziurgota was hospitalized and his attacker was arrested and earned himself a lifetime ban, the Telegraph said.
The Croatian Boxing Federation responded in a statement saying it "met in an emergency session and reached a decision on the suspension and lifelong exile from boxing of boxer Vido Loncar. Until the end of the investigation the executive committee has also suspended the trainers who were at ringside for the terrible event.''
YouTube video of the incident has been viewed over 2.5 million times as of Wednesday: