A chuckwagon rolled on Tuesday morning while coming around a barrel. Tim Haroldson, who was riding as a passenger, was thrown from the wagon and taken to hospital by ambulance. He is a chuckwagon driver, but the wagon was driven by Jerry Bremner, who was not hurt.
"We are hoping for the best for Tim," said Paul Rosenberg, a Calgary Stampede spokesman in a statement.
Stampede officials are reviewing the incident, but say there appears to be nothing out of the ordinary related to the wagon, horse or tracks.
Also during morning training, a wagon horse belonging to Reg Johnstone collapsed and died after completing the team's training run.
"The horse was a 12-year-old thoroughbred named Denny, which had been owned by Johnstone for approximately five years. It was acquired from another chuckwagon driver after its initial career as a racehorse in the Vancouver area. The horse had last raced about a week ago at the Ponoka Stampede," officials said.
A post-mortem will be performed on the horse to determine the cause of death.