(S (S (S (BASENP (DT The) (NN fire)) (VP (VP (VBD was) (ADVP (RB reportedly))) (NP (BASENP (DT the) (NN cause)) (PP (IN of) (BASENP (DT the) (NN explosion)))))) (COMMA ,) (SBAR (IN although) (S (BASENP (DT this)) (VP (VBZ is) (S (VP (ADVP (RB yet)) (VP (TO to) (VP (VB be) (VP (VBN confirmed)))))))))) (PERIOD .))