Five Thoroughbred fillies scheduled to be sold at the Keeneland September Yearling Sale were killed Thursday when a fire believed caused by lightning destroyed a barn at Oscar Penn Jr.'s Penn Farm near Lexington, Ky.Farm manager Sam Penn said the fillies were not insured and had total value of between $150,000-$175,000. Two of the fillies were sired by The Deputy, one by Wolf Power, one by Unaccounted For and one by Down the Aisle. He said the Wolf Power filly was a half-sister to a recent grade III winner in Japan and was the most prominent of the five. He said all of the fillies were either owned by the farm or were part of foal-share arrangements with other breeders, who had been notified of the fire.Penn said the fire was reported at 9:30 p.m. (EDT) and the 300-foot-by-53-foot building was completely engulfed by the time units from the Lexington Fire Department arrived. He said the remains of the barn were still smoldering as of 9 a.m. Friday.Speculation centered around lightning as a probable cause, as a severe storm struck the area about three hours before the fire was detected, Penn said, noting the possibility that a small fire smoldered before the entire barn caught on fire.Penn noted the timing of the fire could not have been worse because the fillies usually would not have been in the structure at night. However, an accident earlier in the day caused a vehicle to go through a fence in the fillies' paddock. Since the fence was not repaired Thursday, the fillies were put in the barn for the night."Whatever could go wrong, did," Penn said of the day's events.