(S (S (BASENP (NN Police) (NNS sources)) (VP (VBP believe) (SBAR (S (NP (BASENP (DT the) (NN bomb)) (PRN (COMMA ,) (VP (VBN estimated) (S (VP (TO to) (VP (VB contain) (NP (BASENP (QP (RB between) (NN 80) (CC and) (NN 100)) (NNS kilograms)) (PP (IN of) (BASENP (NNS explosives)))))))) (COMMA ,))) (VP (VBD was) (VP (VP (VBN detonated) (ADVP (RB remotely))) (PP (IN by) (NP (BASENP (NN one)) (PP (IN of) (NP (BASENP (DT the) (NN two) (NNS attackers)) (SBAR (WHNP (WP who)) (S (VP (VBD fled) (PP (IN in) (BASENP (DT another) (NN vehicle)))))))))))))))) (PERIOD .))