Seven more polo horses have died overnight to bring the death toll to 21 animals that were supposed to play in a Florida tournament.

Veterinarians were waiting for test results Monday to determine why the horses fell ill and died in a short time before their match.

The International Polo Club Palm Beach said the horses from the Venezuela-based Lechuza Caracas team were being unloaded from their trailers Sunday when two collapsed and others acted dizzy and disoriented.

Seven of the horses died on the polo club grounds and the rest died after they were taken away. The Palm Beach Post reported that seven more horses died overnight in treatment or en route. A veterinarian who was at the polo tournament could not be reached for comment Monday