[Lordzy]

You need to get those positions through edges, that's what I normally do.

pawn Код:

/* 
         ymax
     |----------|
     |          |
xmin|          | xmax
     |          |
     |----------|
         ymin
//From wiki sa-mp

To avoid colliding, you can use global variables for gangzones so that the specified functions for a gangzone works for it only. If you're thinking of the visual (Radar), you might be needed to be careful while setting the coords.

Or maybe creating a gangzone according to range may work:
(I probably use this if I'm lazy to get all those coords)

pawn Код:

CMD:gangzone(playerid, params[])
{
 new Float:xp, Float:yp, Float:zp;
 GetPlayerPos(playerid, xp, yp, zp);
 #pragma unused zp
 new range = 100;
 new Gangzone = GangZoneCreate(xp-range, yp-range, xp+range, yp+range);
 GangZoneShowForAll(Gangzone, 0xFF0000FF);
 return 1;
}