Golden Flash Crash

Gold just plunged by $20 for no reason whatsoever. So let's take a guess at what happened here: some ETF caused the NYSE to hit LRP thresholds, causing numerous stocks to "break", and the result is an immediate algorithmic margin call satisfied by gold selling? Or not, at his point does anyone really care. Point is obvious: scare all holders into submission. Can the royal "they" just confiscate everything not in paper form (and thus out of Fed control) already and end this charade?

Update: and gold is now back to pre crash levels. Thank you Johnny 5.