(S (S (PP (BASENP (NN 警察)) (INP (IN に) (VB よる) (INCON と))) (COMMA 、) (S (PP-SBJ (NP (S-REL-NSBJ (VP (PP (NP (PP (BASENP (NN 競技) (NN 場)) (IN の)) (NN 中央)) (IN に)) (VP (VP (VP (VBO 埋め) (VP (VBV られ))) (INTE て)) (VP (VBV い) (VP (MD た)))))) (NP (PP (BASENP (NN ２) (NN 発)) (IN の)) (NN 爆弾))) (IN が)) (VP (VP (NN 爆発) (VBV し)) (VP (MD た))))) (PERIOD 。))
警察 に よる と 、 競技 場 の 中央 に 埋め られ て い た 2 発 の 爆弾 が 爆発 し た 。
According to police , two bombs , which had been planted in the middle of the pitch , were detonated .