So this move is planned including some of their employees. Twitter should investigate every single of those personnel they had, they are not sure whose the culprit Im not a negative thinker but I dont want to assume that even them could part of this. No one knows, how could a security breached instantly? Top executives of their firm might be considered as part of it.
I hope all those who were hacked sue twitter for such violation, and of course, that the hackers be caught as well.
This will be due process but I do hope they do, with money collected by this hacked this will not be tolerated by authorities and demand a response from Twitter. It might be hard to track identities of those hackers using blockchain but I wish they be caught.