DENVER (CBS4) – A 25-year-old bull rider is dead after an event at the National Western Stock Show Tuesday night. He was identified as Mason Lowe by Professional Bull Riders CEO Sean Gleason in a tweet.

Gleason said ” We are deeply saddened to report that Mason Lowe passed away this evening following injuries sustained at the PBR event in Denver. The entire PBR and National Western sports family extends our heartfelt condolences and deepest sympathies to Mason’s wife Abbey and his family.”

Lowe competes during the PBR Kansas City Invitational at Sprint Center on 2017 in Kansas City. (credit: Jamie Squire/Getty Images Sport)

A witness who was at the bull riding event told CBS4 Lowe was bucked off and then the bull stepped on his chest. Apparently Lowe got up, took a few steps and then collapsed.

National Western Stock Show (credit: CBS)

Another witness, Aurora resident Gerardo Alvarez, told CBS4 “He was thrown off the bull and while he was on the ground the back legs stomped him in the chest while he trying to get up. When he got up he immediately grabbed his chest and stumbled over to the exit and then fell to the ground again grabbing his chest before he could get out of the area. They took him out on a stretcher.”

Lowe rides Cochise during the 15/15 round of the PBR Kansas City Invitational. (credit: Jamie Squire/Getty Images)

Lowe was from Exeter, Missouri, and was one of the top ranked bull riders in the world.

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The bull he was riding is named Hard Times.

Last weekend Lowe posted video on his Twitter account of one his bull rides.

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PBR and NWSS announced a website to donate to Lowe’s family.