#include <a_samp>
new NewsArray[2] = {  // instead of 2 input the number of total messages possible
    "NewsMessage1",
    "NewsMessage2"
};

new News_Timer = 0;

/*OnGameModeInit*/
SetTimer("TimeTest_News", 1000, 1);

TimeTest_News()
{
    News_Timer++;
    if(News_Timer > 179)
    {
      new rand = random(sizeof(NewsArray));
      Announce_News(rand);
      News_Timer = 0;
    }
}

Announce_News(id)
{
    SendClientMessageToAll(0xFFFFFFFF, "* ANNOUNCEMENT *");
    SendClientMessageToAll(0xFFFFFFFF, NewsArray[id]);
}