(CNN) -- State officials said Monday that they suspect a drug reaction or toxins killed 21 horses as they were prepared to compete in a Sunday polo match in Wellington, Florida.



Blue tarps obstruct the view of horses that died at the International Polo Club Palm Beach in Florida.



State officials and local law enforcement also announced Monday that they are launching investigations into the deaths as scientists work to pinpoint what exactly killed the horses.



Officials believe that the "very rapid onset of sickness and death" points to toxins or a drug reaction and also allows them to rule out other possibilities.



"At this time, there is no evidence that these horses were affected with an infectious or contagious disease, as there are no other horses affected at this time," according to Florida Agriculture and Consumer Services spokesman Terence McElroy.



Officials are continuing to conduct tests, and Florida agriculture scientists are performing necropsies on the animals.



"We'll be testing blood and tissue to see what the common denominator was here: Was it something injected? Was it bad water? And so forth," McElroy said.



John Walsh, the Lechuza Caracas polo club president, said he was told that there was no contagious virus airborne or disease and that the incident was an "isolated" one.   Watch Walsh talk about the devastating deaths »



"This was a mistake of a combination of something, and whether the mistake was at the barn, whether the mistake was at the feed company, whether the mistake was at the vitamin company," Scott Swerdlin of the Palm Beach Equine Clinic, who treated some of the horses, told CNN affiliate WPTV. "We don't know, but we're going to find out."



James Belden, a veterinarian at the Left Bank Equine Clinic who also treated some of the horses, told WPTV that he and others don't suspect foul play.



"I think this is an accident," he told WPTV. "A terrible accident."



McElroy said that despite the early indications, he does not want to jump to conclusions about what happened.



"Obviously, this is a tragic situation, and we are working hard to determine what happened," he said. "But it would be irresponsible to speculate on what may have killed the horses. We will wait until the facts are in before making any specific comments on the case."



Officials in the state Agriculture and Consumer Services Department will investigate the case with the help of the department's Division of Animal Industry, the department's Office of Agricultural Law Enforcement and other law enforcement agencies.



The horses were part of the Venezuela-based Lechuza Caracas team and were being kept at the team's trailers on the grounds of the International Polo Club Palm Beach.



Fifteen horses that seemed disoriented died before Sunday's match, said McElroy, and their bodies were sent to the state-run Kissimmee Diagnostic Laboratories near Orlando, Florida.



Luis Escobar, a player on the opposing Team Blackwatch, was on the grounds when the horses began to fall ill.



"I thought it was something temporary, and I saw a veterinarian and thought maybe it was one or two horses, and the vet was going to give something to help them out, and it was going to be done," he said. "But it wasn't."



Two horses initially collapsed, and as veterinarians and team officials scrambled to revive them, five others became dizzy, Tim O'Connor, spokesman for the polo club, said Sunday.  Watch as vets search for clues »



Escobar said soon things got worse, and other horses started to get sick.



Peter Rizzo, executive director of the United States Polo Association, was at the match and saw the horses drop.



"It was surreal," he said, calling the deaths "unprecedented."



"It is a horrible tragedy," he said.



Some of the 15 horses died immediately, but some lingered for about 45 minutes, Swerdlin said Sunday, according to a report in the Sun-Sentinel newspaper. The clinic is the International Polo
What did officials say? How many horses died? Who is investigating? Where have a lot of horses died? What have officials ruled out? Where did the deaths occur?
that they suspect a drug reaction or toxins killed 21 horses 21 Officials in the state Agriculture and Consumer Services Department Wellington, Florida. infectious or contagious disease, Wellington, Florida.
question: What did officials say?, answer: that they suspect a drug reaction or toxins killed 21 horses | question: How many horses died?, answer: 21 | question: Who is investigating?, answer: Officials in the state Agriculture and Consumer Services Department | question: Where have a lot of horses died?, answer: Wellington, Florida. | question: What have officials ruled out?, answer: infectious or contagious disease, | question: Where did the deaths occur?, answer: Wellington, Florida.