Authorities are investigating the circumstances surrounding 10 horses missing from their pasture near Sparks, Oklahoma.

Lincoln County Sheriff's Department investigator Larry Stover said the horses' owner reported the animals were missing from their pasture on Aug. 11. An eleventh horse was later found by its owner, he said.

Stover said all the missing horses are mares, and are valued at a total of $40,000.

“These are very expensive horses,” Stover said. “One Palomino alone is valued at $10,000