Anyone ever heard of this?
 

'97 Blazer LT 4x4 4.3L 242K miles. I was getting off the highway one day and I turn onto one of the side streets with everything working perfectly fine. Then out of nowhere I hear a clicking noise that gradually gets louder, with seemingly equal time between clicks. Then the engine cut off while I was moving at about 40mph. Battery is good, alternator is good, fuel pump engages, fuel filter is new, full of oil. When I go to start it I get a loud grinding noise. I've had some people say that the starter tried to engage while I was driving and the bendix got jammed to the flywheel. Now I know this occurs, but I'm not so sure about it happening while the vehicle is moving and under power, because shouldn't there be no power being supplied to the starter solenoid at that time? I have a remote start also, if that matters at all. I'm only asking on here because the blazer is an hour away at my dads where it broke down and I can't get to it til next week. So I'm just trying to put my mind at ease because I really hope the engine isn't seized...

timing chain could have broke, flexplate could have broke and wedged in there. its kinda one of those things where you really cant tell until you look at it, although it can be possible for the starter to just engage itself while driving but ive never heard of that happening