(S (S (PP (IN At) (BASENP (RB around) (NN noon))) (COMMA ,) (S (NP (BASENP (NNS police)) (PP (IN on) (BASENP (NN scene)))) (VP (VP (VBD entered) (NP (BASENP (DT the) (NN section)) (PP (IN of) (BASENP (NN pipe))))) (COMMA ,) (S (VP (ADVP (RB only)) (VP (TO to) (VP (VP (VB emerge) (ADVP (BASENP (DT a) (JJ few) (NNS minutes)) (RBR later))) (PP (IN without) (BASENP (DT the) (NNS protesters)))))))))) (PERIOD .))