07/13/2013 02:08 EDT | Updated 09/11/2013 05:12 EDT

Horse dies at Rangeland Derby, Stampede officials say

A horse has died at the Rangeland Derby, a spokesperson for the Calgary Stampede said late Friday night.

The horse was one of Doug Irvine's outrider horses. Stampede spokesperson Bonni Clark says the horse collapsed and died just after finishing heat 4 during Friday's night's competition.

"Our thoughts are with Doug and his outfit on the loss of Hughey, a 12 year-old thoroughbred which had been part of Doug's team for 5 years," said Clark. "A vet was on the scene and determined the horse died immediately of natural causes."

A post-mortem will be done to pinpoint the exact cause of death. The Stampede says it's thoughts are with Doug Irvine and his outfit on the loss.

"The horse had been inspected prior to the race as part of the Stampede's fitness-to-compete program, and it exhibited no sign of illness at that time. We acknowledge the death of an equine athlete at a public event can be upsetting for some people," said Clark.