The British boxer Sherif Lawal, a 29-year-old middleweight, collapsed during his debut fight on Sunday and was pronounced dead that night at a hospital in London, fight organizers said Monday. An exact cause for the shocking death was not immediately released. Lawal had been fighting against Malam Varela, of Portugal, when he was knocked down during the bout’s fourth round. The match had been scheduled to span six rounds. “Unfortunately during Sherif’s fight, he collapsed and despite the best efforts of the paramedics, he was later pronounced dead,” said the promoters, Warren Boxing Management. The fight was the first on Sunday’s card, and the ensuing fights were called off. It’s the highest profile death in a professional boxing ring since American boxer Patrick Day died from injuries he sustained in a 2019 fight. That incident took place four years after the Puerto Rican boxer Prichard Colón infamously sustained repeated blows to the back of his head that sent him into a coma for months. Today, Colón relies on a computer to communicate simple sentences.