The weird thing is, they have never had maintenance works without prior announcements in the past. And coincidently, bitcoin prices have been crashing since btc-e went down.
Time to put on those reading glasses, the initial tweet said "Unplanned maintenance" , kinda hard to announce needed maintenance when you dont know its needed
Probably just a hardware issue with the servers, hopefully not a hack. And the drop in Bitcoin price wasnt THAT huge really, we see those kind of swings all the time with BTC-E never being offline. Price is on its way back up again now.