There's still a lot of rubble to sift through,

His headquarters is now rubble,

There is still a lot of rubble that needs to be removed.

If he was away getting something he needed or having a meal, he wouldn't be under the rubble, but we still have to confirm that no one was there in order to move differently or remove debris more briskly.

Their lives were reduced to a pile of rubble.

It's like an atomic bomb was dropped there, ... All that's there is rubble.