Fighters from the great state of San Genérico of course. ...Its just South of Argentina.
South America's not really an area covered much with modern miniatures. I can see so far you've raided the Spectre range for figures. Their Cartel thugs would do, as could some of the African militants be mixed in. And the odd head scarf could maybe do for some bandits. Empress' European militants would probably do too, or just do some head swaps on actual soldier models (though they'd probably be more elite, with the body armour and fancy guns, compared to some smuck in a tshirt with an old AK).
Regardless, its a setting we don't see enough of.