"Middle Eastern origin" in my original post should now be changed to "South Asian", as the couple were apparently Pakistani. The wife, however, grew up in Saudi Arabia.

And it's now officially being called an act of terrorism (3,000 rounds of ammunition found in their home along with pipe bombs, and a pledge of allegiance to ISIS by the wife on Facebook).

It does make you wonder what they actually had planned before they lost their focus and shot up a work holiday party.