A chuckwagon driver is hurt and a horse is dead following two unrelated incidents during training exercises at the Calgary Stampede.

A chuckwagon rolled 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.

Tim Haroldson, a chuckwagon driver, was hurt Tuesday morning at the Calgary Stampede. (CBC)

Bremner says it was a freak accident and everything appeared fine up to that moment.

“This has shook me up. I've never had it happen, never at an event in 30 years. A very good friend. You know it's very scary. I pray for him," said Bremner.

"There was nothing out of the ordinary. Everything was going as planned. We turned the top and, horses working great. I mean I don't have an explanation. It's like we caught a little bit of an edge and it was enough to tip us up and tip us over."

A family member says Haroldson is expected to recover.

"We are hoping for the best for Tim," said Paul Rosenberg, a Calgary Stampede spokesman in a statement earlier Tuesday.

Stampede officials are reviewing the incident, but say there appears to be nothing out of the ordinary related to the wagon, horse or tracks.

Horse death

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.