(S (S (BASENP (NNS Police)) (VP (VP (VBD launched) (NP (BASENP (DT an) (NN investigation)) (PP (IN into) (BASENP (DT the) (NN incident))))) (CC and) (VP (VBP have) (VP (VP (VBN deployed) (BASENP (JJ additional) (NNS personnel))) (S (VP (TO to) (VP (VP (VB guard) (BASENP (DT the) (NN area))) (S (VP (TO to) (VP (VB prevent) (BASENP (NN revenge) (NNS attacks)))))))))))) (PERIOD .))