(S (S (S (BASENP (DT The) (NN accident)) (VP (VP (VP (VBD occurred) (PP (IN at) (BASENP (NN 7:10) (NN p.m.)))) (PP (IN on) (BASENP (NNP Thursday)))) (PP (IN in) (NP (BASENP (DT an) (NN area)) (PP (IN of) (NP (BASENP (JJ military) (NN airspace)) (SBAR (WHNP (WDT that)) (S (VP (VBZ is) (VP (ADVP (RB sometimes)) (VP (VBN closed) (PP (TO to) (BASENP (DT the) (NN public)))))))))))))) (COMMA ,) (SBAR (IN although) (S (NP (BASENP (PRPD its) (NN status)) (PP (IN at) (NP (BASENP (DT the) (NN time)) (PP (IN of) (BASENP (DT the) (NN accident)))))) (VP (VP (VBD was) (RB not)) (VBN known))))) (PERIOD .))