Jockey George Baker has been airlifted to hospital after a fall during a race at St Moritz in Switzerland.
Baker was riding Boomerang Bob for Jamie Osborne when the horse was brought down and was fatally injured in the first race of the day.
Three horses came down in the incident but the other two and both of their riders escaped injury.
Baker was taken to a trauma hospital in Chur and the rest of the meeting was abandoned.
St Moritz press officer Claudia Grasern-Woehrle said: "We checked the track following the incident and we have found a hole in it, which means we have had to cancel the rest of the meeting as safety comes first."
Racing has taken place for decades on the frozen lake at St Moritz, with horses fitted with special shoes to cope with the wintry conditions.
Baker won the world's oldest classic, the St Leger, last September on Harbour Law.