A Tomah couple and their two grandchildren were found dead Friday morning in their trailer while camping out for the World Clydesdale Show in Madison this past weekend.

Those found sleeping in the trailer were De Vere Clay, 68, his wife Barbara Clay, 57, and their grandchildren Hope Briney, 13, and Erin Briney, 10. According to a release from the Dane County Coroner's Office, the family died of carbon monoxide poisoning while sleeping in their horse trailer outside the Alliant Energy Center.

Town of Madison police officers were the first to arrive on the scene at approximately 7:47 a.m. after they were dispatched by the Dane County Community Center. Police Chief Scott Gregory said the community center was alerted of the incident when it received a call from a family member of the deceased that morning.

"They located four people that appeared to be deceased," Gregory said of the officers who arrived at the scene first. "[The four] were at the Alliant Energy Center for the Clydesdale Association horse show."

According to a release from the Town of Madison Police Department, the initial investigation indicated the carbon monoxide came from an old propane heater used to heat the trailer.

Barcklay Poole, marketing director for the Clydesdale Breeders of the USA, said the family was a well-known breeder and exhibitor within the Clydesdale community. However, despite the unexpected start to the weekend of horse showing, Poole said the event went considerably well.

"After what happened, everybody kind of regrouped and decided the show must go on," Poole said, which was partly an effort to show support and tribute to the family. "It was an awesome show in terms of attendance. The competition has been phenomenal."

Poole said well over $10,000 has been collected at the show for the family of the victims. The show also observed a moment of silence for the family before the afternoon program of each day's events.