I think it started cause of SegWit. What we have now is good old panic.
It ll pass in a few days, we ve seen this before.
It s also great time to buy.
Eth is now worth $190 but there was a time when it dropped even more than now. Now might be an indeed good time to buy some but as I once bought eth and got it stolen, I just don't feel like buying right now.
I agree that this is definitely not a reason to panic, everything will return to normal in a few days.
Perhaps now is also a good time to buy ltc even though it is not suffering much from current big drop of prices.