(S (S (S (BASENP (NNS Passengers)) (VP (VBD were) (VP (ADVP (RB initially)) (VP (VP (VBN kept) (PP (IN on) (BASENP (NN board) (DT the) (NN aircraft)))) (PP (IN before) (S (VP (VBG being) (VP (VBN allowed) (S (VP (TO to) (VP (VB get) (PRT (RP off))))))))))))) (COLON ;) (S (S (BASENP (DT the) (NN plane)) (VP (VBD was) (VP (VBN moved) (PP (TO to) (NP (BASENP (DT a) (JJ secure) (NN section)) (PP (IN of) (BASENP (DT the) (NN airport)))))))) (SBAR (IN while) (S (BASENP (NN police)) (VP (VBD investigated) (BASENP (DT the) (NN incident))))))) (PERIOD .))