An exercise rider has died after a horse collapsed and fatally crushed him at Toronto's Woodbine Racetrack on Tuesday -- an incident which officials are describing as a "freak accident."

Mourad Boudraa, 40, was in the saddle doing exercise runs at around 6 a.m. when the 3-year-old female thoroughbred he was riding broke into an unexplained gallop. The horse, named Tawney's Wish, crashed through a rail and then collapsed on Boudraa, police said. He suffered severe head injuries and was crushed by the weight of the animal. Both Boudraa and the horse were pronounced dead at the scene.

"I would say it's a freak accident," Jamie Martin, vice-president of Woodbine Entertainment Group, told reporters on Tuesday.

Boudraa, who is originally from Morocco, was a father of three children. Two live in Toronto, and one lives in Morocco. Martin said the exercise rider had three to four years of experience, and had worked with a number of trainers.

Police told CTV Toronto that the horse suffered a medical incident that may have been a heart attack, but the cause of death will not be confirmed until a necropsy is performed.

The horse's body has been sent to the University of Guelph for examination. Necropsies are performed whenever a racehorse dies.

Martin said the Tawny's Wish was new to racing, and had only run in one race before. She had $368 in winnings.

"It was unfortunately just a terrible fluke accident," Martin said.

"Our hearts and sympathies go out to Mourad Boudraa's loved ones in this sad and very difficult time."

The Ministry of Labour has launched an investigation into the incident.

With a report from CTV Toronto's Zuraidah Alman