TORONTO - An exercise rider died this morning after being crushed by a thoroughbred at Toronto's Woodbine Racetrack.

The rider was identified by racetrack officials as 40-year-old Mourad Boudraa.

Toronto police say the rider was crushed into the track railing and then by the weight of the horse as it collapsed.

Police say the horse had gone into an unexplained wild gallop and showed signs of medical distress.

The horse was a three-year-old filly called Tawney's Wish.

It had one start this year and 368 dollars in winnings.

Woodbine Racetrack officials say the horse is believed to have died of a heart attack.

The Ontario Racing Commission requires a necropsy whenever a racehorse dies.

Officials from the provincial Ministry of Labour are investigating the accident.