Crazy thing happened, now car won't start

[essial]

OK, I'm driving down the road feeling pretty good -- I adjusted my TPS sensor (due to it idling low before I ran seafoam through it), and now it's driving like a CHAMP, and it's properly down shifting (automatic) when pedal is pressed down. Well as I start down one of the hills on the way home, my rpm just goes to zilch, and gas does nothing (I now think the engine shut off). I shifted to 2nd and it seemed to come back up for a second but then again back to zilch. Now when I turn the key it just keeps turning over trying to start, but does absolutely nothing else (but there's no weird sounds, just sounds like it's normally trying to start). The engine doesn't sound weird, fluid levels look good, and not a single drip is falling underneath the car. The tow truck guy just towed it 1/4 a mile to my house. Any idea whatsoever happened, and any idea what could be the problem?

(Note: It's a 7M-GE automatic)