Well, this could be of course. But it wouldnt be the first time newsreporters/sites place articles or broadcasts online before the event...

Here is the link, I tried to confirm the date google indexed it first. But I guess im not that tech savy...
http://www.wgow.com/news/stephen-paddock-heres-what-we-know-about-the-las-vegas-shooter/
So i hope someone can confirm the date?

The above link gives me the following result now:

I remember scanning the article and noticed it might be updated be cause it linked to this article CNN (posted on oct 3th):
http://edition.cnn.com/2017/10/02/us/las-vegas-attack-stephen-paddock-trnd/index.html