My WAG is that you hit a patch of slick stuff (especially that smooth crude oil looking stuff they use to repair cracks) and the wheel slipped enough to lockup. That would kill the engine and it can keep the wheel locked. If you were in one of the 3 lower gears, it's even more likely that the engine will stop the wheel from regaining traction.
Glad you're not busted up any more than that, you are sure to heal up in a few. Too bad bikes don't heal up too.
