A Feb. 5 fire in a barn at Eureka Downs in Eureka, Kan., killed 43 horses and remained under investigation as of Feb. 6, officials said.Both Thoroughbreds and Quarter Horses, most of which were 2-year-olds in training, were killed. Eureka firefighters said the cause of the fire is under investigation by the Kansas fire marshal.One horse, 5-year-old Smart Effort, escaped the blaze. "It burned 25% of his body on his right side and singed his hair off, but they think he will make it," said Eugene Ralston, a member of the board of directors of the Kansas Quarter Horse Association.Ralston also said one trainer lost 23 horses --his entire stable-- in the fire.Firefighters said the barn was in flames when they arrived, and the horses died before they could contain the fire. It required about three hours and three fire engines to extinguish the fire, the Associated Press reported. The barn was built in 1989 and had 90 stalls. Track official Dick Clasen told the AP it would take days to determine total losses.Eureka Downs, owned by the Greenwood County Fair Association, holds races from May-July and is a year-round training facility.