(S (S (PP (IN Amid) (NP (BASENP (DT the) (NNS confusion)) (VP (VBG surrounding) (NP (BASENP (NN today) (POS 's)) (BASENP (NNP London) (NNS blasts)))))) (COMMA ,) (S (BASENP (NNS officials)) (VP (VBP have) (VP (VP (VBN urged) (BASENP (DT the) (NN public))) (S (VP (TO to) (VP (VP (VP (VB avoid) (BASENP (DT the) (NN city))) (SBAR (IN if) (FRAG (ADJP (JJ possible))))) (S (VP (TO to) (VP (VB allow) (S (BASENP (NN emergency) (NNS services)) (VP (TO to) (VP (VB operate) (ADVP (RBR more) (RB quickly))))))))))))))) (PERIOD .))