(S (S (SBAR (WHADVP (WRB When)) (S (NP (BASENP (NN police)) (CC and) (NP (BASENP (NNS officials)) (PP (IN from) (BASENP (DT the) (NNP Food) (CC and) (NNP Environmental) (NNP Hygiene) (NNP Department))))) (VP (VBD attempted) (S (VP (TO to) (VP (VP (VB remove) (BASENP (DT the) (NNS sculptures))) (PP (IN on) (NP (BASENP (DT the) (NNS grounds)) (PP (IN for) (S (VP (VBG obstructing) (BASENP (JJ public) (NN access))))))))))))) (COMMA ,) (S (BASENP (PRP they)) (VP (VBD were) (VP (VP (VP (VBN prevented) (PP (IN from) (S (VP (VBG doing) (ADVP (RB so)))))) (PP (IN by) (BASENP (NNS activists)))) (PP (IN for) (BASENP (NN two) (NNS hours))))))) (PERIOD .))