(S (S (BASENP (NNS Police)) (VP (VP (VBP are) (VP (VBG cautioning) (SBAR (IN that) (S (NP (BASENP (NN CS) (NN grenade) (NNS launchers)) (CC and) (BASENP (JJ explosive) (NNS entries))) (VP (MD could) (VP (VB be) (VP (VBN mistaken) (PP (IN for) (BASENP (NNS shots)))))))))) (CONJP (COMMA ,) (CC and)) (VP (VBP have) (VP (VBN said) (SBAR (IN that) (S (BASENP (DT no) (NNS shots)) (VP (VBD were) (VP (VBN fired))))))))) (PERIOD .))