If no one else was involved, why did a woman show up at the concert, warning everyone there that they were About To Die..?
My biggest concern is Jose, the hotel worker, who supposedly ‘responded’ to the shooting then turns out he has enormous amount of Gun Shot Residue (GSR) on his hands. GSR does not lie. It is only produced by combustion of a bullet, i.e. it’s firing. You can handle all the ammo you want but not have GSR. You only get it from firing a weapon.
IMO, Jose knew Paddock was a weapons dealer and planned to rip him off. After killing him and stealing his guns and money he needed a cover. His team included the woman who upon learning of the shootup about to occur told the concert goers they were going to die. Jose shoots the fuel tank to create a diversion. When the fuel tank fails to ignite he tells his team he’s going to shoot the concert goers.