New Zealand Thoroughbred Racing has launched an investigation into the deaths of three horses at Auckland's Ellerslie Racecourse on Monday.
Two were euthanised after falling and injuring themselves in hurdle races, another after it was injured in the steeple chase.
Thoroughbred Racing general manager of racing and handicapping Matthew Hall said it was not normal for three horses to die in one race day.
"We've immediately launched an investigation into how the deaths have occurred, and we'll be doing everything we can to ensure any safety improvements required are made."
A racing expert agreed it was unusual to have so many horses die in a single race day.
The horses - Tu Meta Peta, Musashi and Bahhton - were all euthanised on the track after they fell and suffered fractures during races.
Dennis Ryan, national jumps racing coordinator at NZ Jumps, has labelled Monday's deaths sad, saying no one wants to see horses die."I think last year there was a grand total of three fatalities across the whole winter season. It was definitely out of the ordinary."
Mr Ryan is rejecting calls by animal rights group Safe to ban the sport, but admits jumps racing is "inherently riskier than flat racing".
He said Thoroughbred Racing was doing its best to minimise that risk.
"There are always measure being brought in to lessen the danger to both horses and riders."
Mr Ryan said the deaths at Ellerslie will be studied, and hopefully the industry will learn something from it.
Safe campaigns head Mandy Cater said it was only matter of time before the first horses were killed in this year's jumps race season.
"Jumps racing is impossible to make safe, as by its very nature, there is a constant risk to the horse. Horses are dying on race tracks every year and the casualties will continue to mount unless action is taken," she said.
"People are betting, while owners and trainers are making money, and it is costing the horses their lives. The only solution is to ban jumps racing."
Safe is urging people to sign an online pledge not to bet on jumps racing.