They said the ERP , whose fighters first appeared wearing military fatigues and brandishing assault rifles in the southwestern state of Guerrero on June 28 , had a 23,000-strong membership , but this could not be confirmed independently .
<response> They said the <organization>ERP</organization> , whose fighters first appeared wearing military fatigues and brandishing assault rifles in the southwestern state of <location>Guerrero</location> on June 28 , had a 23,000-strong membership , but this could not be confirmed independently . </response>