The bull, named Hard Times, bucked the beloved 25-year-old star off its back and stomped on his chest, killing him during the Professional Bull Riders (PBR) Chute Out event at the National Western Stock Show in Denver.
“The bull absolutely unintentionally injured and killed Mason,” PBR CEO Sean Gleason told the Denver Post. “… In this particular case, he had no idea that Mason had been sucked underneath him. The bull did not do this with any mal-intent.”
Despite wearing a protective vest, Lowe suffered a “massive chest injury that caused damage to his heart,” PBR officials said.
“Mason was pulled under his bull during the buck off and the bull’s hind left leg struck him in the chest,” PBR president Sean Gleason told FOX31 Denver. “The material inside is designed to disperse the weight. In this particular case, Mason took a shot that was -- that no vest probably would have helped.”
Tuesday’s competition marked the first time Lowe had ridden Hard Times, according to the Denver Post. Bulls in the competition can weigh as much as 2,000 pounds.
Bull riding fans returned to the Denver Coliseum on Wednesday night to pay tribute to Lowe, who was ranked 18th in the sport worldwide at the time of his death. His bull riding career spanned seven years.
The National Western Stock Show and PBR set up a fundraiser to support Lowe’s wife and family.
Fox News' Katherine Lam contributed to this report.