sign, interrupted

I woke up Sunday morning to see a street sign lying on the ground, injured or dead (who can say?). The sign had two messages affixed to its pole: one prohibiting parking from the posted spot to the corner, the other permitting parking on odd-numbered days starting at 6 p.m. How the sign found itself in the prone position, rather than the standard vertical one, is a mystery. It's a mystery to me, but not to everyone. The normally-rooted-in-the-ground metal pole holding the sign's message was severed near the bottom, seemingly sheared. An unbloody stump remained in the ground. How did this happen? It would take some force. A thump was heard in the night, the morning hours. Did a vehicle hit it? I saw no tracks to indicate that. Did Halloween mischief makers make mischief? How? What are we to make of this, if anything at all?