(S (S (BASENP (NNS Rescuers)) (VP (VBP are) (VP (ADVP (RB still)) (VP (VP (VBG looking) (PP (IN through) (BASENP (DT the) (NN wreckage)))) (S (VP (TO to) (VP (VB find) (NP (BASENP (NNS survivors)) (PP (IN of) (NP (BASENP (DT those)) (SBAR (WHNP (WP who)) (S (VP (MD might) (VP (VB have) (VP (VBN been) (VP (VBN killed))))))))))))))))) (PERIOD .))