(S (S (S (BASENP (DT The) (NNP February) (JJ industrial) (NN disaster)) (VP (VBD killed) (BASENP (NN 13) (NNS people)))) (SBAR (WHADVP (WRB when)) (S (NP (BASENP (DT the) (NNP Imperial) (NNP Sugar) (NN refinery)) (PP (IN at) (NP (BASENP (NNP Port) (NNP Wentworth)) (COMMA ,) (BASENP (NNP United) (NNPS States))))) (VP (VBD exploded))))) (PERIOD .))