The boxing world got hit with a stunning tragedy this week as 25-year-old junior welterweight boxer Luis Quinones died on Thursday night as a result of a fight that left him knocked unconscious five days before.

According to ESPN, Quinones was hospitalized on Saturday following a knockout loss to opponent Jose Munoz. Quinones was unbeaten heading into the fight, but he was knocked unconscious by a punch in the eighth round of Saturday’s fight after he was on “wobbly legs,” as ESPN describes.

Following the knockout punch, Quinones was put on a stretcher and taken to the hospital, where he was declared brain dead on Thursday despite being kept alive by a ventilator until his passing.

“Cuadrilatero Boxing is deeply saddened by the death of Luis Quinones, an exceptional and disciplined human being, who always showed the greatest commitment to this sport,” the fight’s promoter said in a statement. “Luis was passionate about boxing, so much so that he left his hometown of Barrancabermeja to continue his career in Barranquilla and become a national athlete. His idol was Julio Cesar Chavez.”

While boxing is an inherently violent sport, the sports world was still stunned by Quinones’ death – especially considering Tua Tagovailoa’s traumatic head injury on Thursday night.

It’s clear that head injuries can be fatal and need to be taken seriously.