One horse was found dead and another so severely injured that it had to be euthanized Friday morning in a field at a Nokesville farm, and police say they are probing the case as “suspicious.”

Someone at the farm near Vint Hill Road first tipped police to the incident, which occurred between 6 a.m. and 7 a.m. Friday, the eve of the famed Kentucky Derby horse race, police said. They said a 10-year-old thoroughbred-cross mare was found dead in the field and a quarter horse gelding palomino was found with injuries so severe it had to be euthanized.

Prince William County Police spokesman Sgt. Kim Chinn declined to describe in detail the injuries the horses suffered, but she said they were “not typical” of what horses might do to one another. She said investigators were unsure whether a crime had occurred or whether the horses might have been attacked by another animal.

“Either one’s possible,” Chinn said.

Chinn said the horses were not kept for racing, but for pleasure and shows. She declined to name the farm where the incident occurred, citing “security” concerns.