Question about the DC Universe....?

ok in the animated series Justice League, Justice League Unlimited, Batman Beyond, and all those series... in a spinoff of I think it was a Justice League Episode, Batman, Wonder Woman, and the Green Lantern all fallowed some villan to the future which ended up to be the Batman Beyonds world. In this episode they talked about the justice league all being destroyed in the tower except for batman... I was just currious if there was something that explained that attack a little bit more. Like is there an episode in some other series that explains it better like who did it and how and if there was a fight...just currious about how the bad guys killed superman, wonderwoman, and all those characters....thanks if you can help!