A reliable Israeli source (Arutz Sheva) is saying the exact same thing:
Las Vegas gunman identified as American convert to Islam
http://www.israelnationalnews.com/News/News.aspx/236219
Reported by who? They don't say. The police haven't even said the name yet, so how do Isreali media know this already? Maybe a case of one anonymous Isreali source being echoed around the media.
Story seems to be changed/updated. They have pulled all reference to Islam. Maybe just waiting for better verification?? Or was it false info?? Don’t know right now....
Then expect this to go down the memory hole.