IF
CharacterEnteredTrigger(_player,TRIGGER_HIB_ZombieAmbush)
THEN
TriggerUnregisterForPlayers(TRIGGER_HIB_ZombieAmbush);
CharacterAppear(CHARACTER_HIB_ZombieAmbush_1,1);
CharacterAppear(CHARACTER_HIB_ZombieAmbush_2,1);
CharacterAppear(CHARACTER_HIB_ZombieAmbush_3,1);
CharacterAppear(CHARACTER_HIB_ZombieAmbush_4,1);