If I remember correctly the rumors started at Alex Jones's Inforwars.com. If not - it's the type of thing he would promote. According to Alex Jones the Sandy Hook massacre was committed by Government agents in order to "take our guns".

As one blogger said you don't need government troops to force people into a Walmart. Just announce a half price sale on ammo,camouflage clothing and frozen chicken nuggets. Then open the doors and stand back.

And do I need to point out that a good share of the Navy Seals and Green Berets that are supposed to be invading were probably from Texas in the first place? It's not like the government has a bunch of Hessian troops waiting in the wings.