Probably just a method of ruling different things out, since they have yet to find an actual cause. Although I'm not saying that it would be a complete shock if it turned out to be related to terrorism (domestic or otherwise).
I'm thinking he didn't mean SWAT in the sense of "Special Weapons And Tactics". We have "SWAT" teams at work when systems failures occur. They are not tacticooled out and toting M4's.
It is the Department of Interior sending the "SWAT" teams. As SWAT (the fellas with guns) teams are generally local LEO, what would the DoI be doing directing them?
While there are military meanings for SWAT, wouldn't the DoD manage them?
The only thing that makes me wonder is the lack of clarification from the WH, as this thing went on Drudge then worldwide pretty quickly.