(S (S (S (NP (BASENP (DT The) (NN cause)) (PP (IN of) (BASENP (DT the) (NN accident)))) (VP (VBZ is) (PP (IN under) (BASENP (NN investigation))))) (CONJP (COMMA ,) (CC but)) (S (BASENP (DT no) (JJ other) (NNS jets)) (VP (VBP are) (VP (VBN said) (S (VP (TO to) (VP (VB be) (VP (VBN involved))))))))) (PERIOD .))