Fire officials say the blaze that destroyed four horse barns and caused other damage at the Kentucky Exposition Center early Tuesday appears suspicious, but no cause has been determined.Federal investigators came to the site Wednesday, bringing with them an accelerant-sniffing dog to search for evidence. A Louisville Metro fire official disclosed to the Courier-Journal that there was a small fire the previous day in another barn, but it was not reported because it was quickly extinguished by staff.Meanwhile, State Fair Board President Harold Workman says an insurance adjuster has also been on the scene, assessing the damage."There's no doubt it will exceed a million dollars, it may even approach two million dollars, because we had four barns detroyed, we had about three others that were seriously damaged, we had some damage to the outside ring, arena, with the fence around it, the speaker system, some of the lights," Workman said.There were no animals in the barns at the time of the three-alarm blaze.