Audio from the street by Mandalay Bay during the shooting, it sounds a lot like two guns being fired from separate locations from the location this was recorded. There's even a recording without echo at the end which should boggle your mind if you know anything about anything.
could be edited tho whoknows.
https://www.youtube.com/watch?v=yQV8mFx0-CQ
so far evidence in support of 2 shooter theory would be the light flashes seen on a lower floor, the police scanners all reporting a shooter on lower floors, and some cell phone audio clips. not quite buying this theory yet but it's one to keep an eye on.