(S (S (PP (IN At) (BASENP (NN 12:30))) (COMMA ,) (S (SBAR (IN after) (S (BASENP (DT an) (NN ambulance)) (VP (VBD arrived) (PP (IN on) (BASENP (NN scene)))))) (COMMA ,) (S (BASENP (NNS police)) (VP (ADVP (RB once) (RB again)) (VP (VP (VBD entered) (BASENP (DT the) (NN pipe))) (CC and) (VP (VBD began) (S (VP (TO to) (VP (VP (VB pull) (PRT (PRT on))) (NP (BASENP (NN one)) (PP (IN of) (BASENP (DT the) (NNS barrels))))))))))))) (PERIOD .))