A fire in an underground electrical transformer vault early Saturday dislodged manhole covers and shut down downtown Louisville blocks.No injuries were reported, said Brian Phillips, a spokesman for Louisville Gas & Electric.Saturday morning, Jefferson Street was closed between Sixth and Ninth streets and Market was closed between Seventh and Eighth streets, a MetroSafe supervisor said.The fire happened at about 7 a.m., Phillips said. The cause of the fire—which is believed to be electrical—had not yet been determined early Saturday.LG&E and Louisville Fire are investigating.The underground vault is at Seventh and Market streets. Road or lane closures in that area could endure to Monday while LG&E crews do repairs, Phillips said.No electrical customers lost service because of the fire, Philips said.