Local veterinarians arrived in force in a desperate bid to save the ailing polo ponies, but in the end 14 of the animals from the Lechuza Caracas team were left dead.
The crowd which had turned up to watch the match could only look on as veterinarians worked on the animals, putting in intravenous drips and helping the animals in whatever way they could, including trying to reduce their temperatures.
However, one by one, they died. It is understood seven died at the ground - the International Polo Club Palm Beach - and seven died while being taken to veterinary hospital for treatment. An earlier report suggested four animals were dead in their trailer on arrival at the grounds.
Reports out of the United States suggest two animals remain ill, including a mare whose condition is serious.
The Venezuelan-based team was scheduled to pay in a match against Black Watch as part of the US Open Polo Championship.
It is understood the horses began showing early signs of distress - heavy breathing and clumsiness - before leaving the Lechuza equestrian base and heading for the polo club.
Florida state veterinary authorities are analysing blood samples and post mortems will be performed on the order of state veterinarian Dr Mike Scott.
The animals are believed to have had a reaction to something and it is hoped tests, the results of which could be known as early as Tuesday next week, will reveal the cause.
The horses are understood to be collectively worth more than $US1 million.
Officials erected blue tarpaulins to shield the animals as vets worked on them.
An investigation is expected to be launched by the US Polo Association.