(S (S (BASENP (JJ Belgian) (NNS authorities)) (VP (VBP have) (VP (VBN confirmed) (SBAR (IN that) (S (NP (QP (ADVP (IN at) (JJS least)) (NN eighteen)) (NNS people)) (VP (VBD died) (PP (IN in) (NP (NP (BASENP (DT a) (JJ head-on) (NN collision)) (PP (IN between) (BASENP (NN two) (NN passenger) (NNS trains)))) (PP (IN in) (NP (BASENP (DT the) (NNS suburbs)) (PP (IN of) (BASENP (NNP Brussels))))))))))))) (PERIOD .))