Competitive fighter Isaac Johnson, 31, has died following an injury at a stadium in Cicero, Illinois, on Friday. 

Johnson collapsed toward the end of his match, according to an event organizer of the Matador Fighting Challenge.

According to Cicero officials, emergency responders were called to the Cicero Stadium, 1909 S. Laramie Ave., just before 8:40 p.m. during a scheduled fight. An injured fighter was taken to Loyola University Medical Center in Maywood. 

Cicero officials confirmed Johnson was pronounced dead Saturday morning. Further information on the circumstances surrounding his death have not been released. 

An investigation is underway by Cicero police.