Same thing that happened on August 2014.
Market maker or other any other major player dumps a big quantity of coins that wipes out an important portion of the whole orderbook which causes a margin cascade of longs closing. Considering that BTC-E is illiquid, this is highly profitable if he has shorts opened that he will soon close/already closed or longs/coins orders at around $150.
Being a shady as hell exchange I wouldn't be surprised if somebody from BTC-E is somewhat responsible himself, having insider info on where all the stops are placed and margin calls would be triggered.
Stop hunts and shenanigans happen in forex everyday, can't see how a shitty anon exchange for magic internet money would be any different.
This, or an Agora drug dealer or admin dumping because he wanted to buy a boat or something.
Still, the results (margin cascade) are the same.
