At least 13 people were killed when scores of masked rebels struck at police and military posts in Oaxaca and Guerrero states overnight in the biggest assaults in more than two years , officials said on Thursday .
<response> At least 13 people were killed when scores of masked rebels struck at police and military posts in <location>Oaxaca</location> and <location>Guerrero</location> states overnight in the biggest assaults in more than two years , officials said on Thursday . </response>