God of lunchboxes
-I am fairly young and therefore have limited knowledge on classic who, like none feel free to fill me in on anything relevant to my theory-
The TARDIS is time lord tech, and it would take someone with expansive knowledge of time lord tech to blow it up and spread destruction (or uncreation?) across the entirety of space-time. So I think a time lord has to be behind this. And although I'm not sure I believe there is a very sinister Time Lord who likes to call himself Omega. At the same time I think he may have been perma-killed.

True, it had to be a powerful force, or something already in the Tardis perhaps...