MMA fighter Isaac Johnson has died after he was injured during his boxing match on Friday, November 21. He was 31. Johnson was competing at the Matador Fighter Challenge at Cicero Stadium in Illinois against Corey Newell when he collapsed towards the end of the third and final round. A town spokesperson told NBC 5 Chicago that an ambulance was called at 8:38 p.m. CT to transport an injured fighter to Loyola University Medical Center. He died a few hours later, at 12:01 a.m. CT, according to multiple outlets. The Cook County Medical Examiner's Office told the outlet that an autopsy was scheduled to determine the cause of death. Cicero police are also investigating the incident. Irish Boxer John Cooney Dead at 28 After Suffering Brain Injury From Fight The fight's promoter, Joe Goytia, confirmed to The Athletic that it was Johnson's first-ever Thai boxing match, referring to the combat sport that uses stand-up striking, sweeps and various clinching techniques. Goytia wrote a Facebook post after the incident, saying he doesn't "have the words to express how I feel right now." "This is a post I hoped to never make, last night one of the fighters in our event Isaac Johnson collapsed towards [the] end of his fight," he said. "Medical attention was given by medical staff on hand and he was transported to hospital. I was then informed at around 130 am this morning that he didn't make it." Isaac Johnson Isaac T. Johnson/Facebook He continued: "I don't have the words to express how I feel right now, all I can say is my deepest condolences to his family, friends, and teammates. We will know more as the medical report is released." Goytia also confirmed that Johnson passed the required physical before the bout. "I'm still processing this. I just don't know," Goytia told The Athletic on Saturday, November 22. "I never in a thousand years (thought) this would have happened." In the interview with the outlet, Goytia described the match as a "slugfest." He also said Johnson's opponent, Newell, was in just his second fight. Both competitors threw punches, Goytia said, but did not connect on many of them and the fighters looked exhausted. He said they were both wearing the proper protective equipment: boxing gloves, shin guards and mouth pieces. He also told the outlet that he couldn't pinpoint a singular moment that caused the injury. Boxer Sherif Lawal Dead at 29 After Being Knocked Out in 1st Pro Match "I really didn't see them land anything that would have been like 'Wow, that's what did it,'" Goytia said to the outlet, adding that he saw nothing unusual during the fight. "In the back of your mind, you know this is a tough sport, you know injuries do happen in sports. But you never think this would happen," Goytia said. "I know all the protocols were followed correctly, but in this case, it didn't work." The event was advertised on its website as "the ultimate MMA and Thai event, where local warriors will battle it out in high-stakes, high-intensity matches." Johnson was fighting in the heavyweight bout. The Illinois Department of Financial and Professional Regulations (IDFPR) is investigating the incident, according to Fox 5 Washington D.C.