(S (S (S (NP (BASENP (DT The) (NN five) (NNS firefighters)) (SBAR (WHNP (WDT that)) (S (VP (VBD were) (VP (VBN killed)))))) (VP (VBD died))) (SBAR (WHADVP (WRB when)) (S (BASENP (PRPD their) (NN truck)) (VP (VBD was) (VP (VBN overrun) (PP (IN by) (BASENP (DT the) (NNS flames)))))))) (PERIOD .))