VIDEO: NV Energy reports that a substation transformer near the Tracy Generating Station outside of Reno caught fire after experiencing an internal failure Sunday afternoon. It happened at 4:25 p.m. according to a representative with NV Energy. NV Energy and fire response crews were called on-site immediately and the fire was extinguished around 7:25 p.m. There were no direct impacts to NV Energy customers. A spokesperson for the Storey County Fire Protection District says the fire was sparked by an explosion and the cause of that explosion is under investigation by both NV Energy and Storey County. The Nevada Department of Environmental Protection has also been contacted. A thick black plume of smoke visible across the area was caused by burning mineral oil according to the SCFPD spokesperson.