(S (S (NP (BASENP (NNS Helicopters)) (PP (IN from) (BASENP (DT the) (NNP US) (NNP Navy)))) (VP (VP (VBD searched) (PP (IN for) (BASENP (NN 13) (JJ missing) (NNS persons)))) (PP (IN until) (NP (BASENP (NNP Friday) (NN morning)) (COMMA ,) (SBAR (WHADVP (WRB when)) (S (BASENP (DT the) (NN search)) (VP (VBD was) (VP (VBN called) (PRT (RP off)))))))))) (PERIOD .))