The oil pump must be dead. I do not know your engine well, but the pump would likely be also driven by the belt. If it had been the alternator, you would not have had much electrical power to even put the blinkers on, though your trip only lasted ten minutes.
You could have serious damage to the engine, by the way. The sounds you described are quite foreboding.
I'm quite sorry to say, but I can't exactly imagine why the oil pressure warning would come on otherwise, and why it would go on for an alternator problem.