(S (S (S (NP (BASENP (DT An) (NN accident)) (VP (VBG involving) (NP (NP (BASENP (NN two) (NN school) (NNS buses)) (COMMA ,) (BASENP (DT a) (NN tractor) (NN trailer))) (CC and) (BASENP (DT an) (NN sport) (NN utility) (NN vehicle))))) (VP (VBZ has) (VP (VP (VBN left) (S (S (NP (QP (ADVP (IN at) (JJS least)) (NN two)) (NNS people)) (ADJP (JJ dead))) (CC and) (S (BASENP (QP (NN fifty) (JJR more))) (ADJP (JJ injured))))) (ADVP (BASENP (QP (RB about) (NN 40)) (NNS miles)) (ADVP (RB outside) (PP (IN of) (NP (BASENP (NNP St.) (NNP Louis)) (COMMA ,) (BASENP (NNP Missouri))))))))) (PP (VBG according) (PP (TO to) (BASENP (NNS reports))))) (PERIOD .))