How can you make an AI character cause damage to the player if it touches it.

If needed my health script is:

var healthdead : Texture2D; //dead
var health1 : Texture2D; //one hit left
var health2 : Texture2D; //two hits left
var health3 : Texture2D; //three hits left
var health4 : Texture2D; //four hits left
var health5 : Texture2D; //five hits left
var health6 : Texture2D; //six hits left
var health7 : Texture2D; //seven hits left
var health8 : Texture2D; //eight hits left
var health9 : Texture2D; //nine hits left
var health10 : Texture2D; //ten hits left
var health11 : Texture2D; //eleven hits left
var health12 : Texture2D; //twelve hits left
var health13 : Texture2D; //thirteen hits left
var health14 : Texture2D; //fourteen hits left
var health15 : Texture2D; //fifteen hits left
var health16 : Texture2D; //sixteen hits left
var health17 : Texture2D; //seventeen hits left
var health18 : Texture2D; //eighteen hits left
var health19 : Texture2D; //nineteen hits left
var health20 : Texture2D; //twenty hits left
var health21 : Texture2D; //twenty one hits left
var health22 : Texture2D; //twenty two hits left
var health23 : Texture2D; //twenty three hits left
var health24 : Texture2D; //full health

static var LIVES = 24;

function Update () 
{
	switch(LIVES)
	{
		case 24:
			guiTexture.texture = health24;
		break;
			
		case 23:
			guiTexture.texture = health23;
		break;
			
		case 22:
			guiTexture.texture = health22;
		break;
			
		case 21:
			guiTexture.texture = health21;
		break;
			
		case 20:
			guiTexture.texture = health20;
		break;
		
		case 19:
			guiTexture.texture = health19;
		break;
		
		case 18:
			guiTexture.texture = health18;
		break;
		
		case 17:
			guiTexture.texture = health17;
		break;
			
		case 16:
			guiTexture.texture = health16;
		break;
		
		case 15:
			guiTexture.texture = health15;
		break;
			
		case 14:
			guiTexture.texture = health14;
		break;
			
		case 13:
			guiTexture.texture = health13;
		break;
			
		case 12:
			guiTexture.texture = health12;
		break;
			
		case 11:
			guiTexture.texture = health11;
		break;
		
		case 10:
			guiTexture.texture = health10;
		break;
			
		case 9:
			guiTexture.texture = health9;
		break;
			
		case 8:
			guiTexture.texture = health8;
		break;
			
		case 7:
			guiTexture.texture = health7;
		break;
			
		case 6:
			guiTexture.texture = health6;
		break;
			
		case 5:
			guiTexture.texture = health5;	
		break;	
			
		case 4:
			guiTexture.texture = health4;
		break;	
			
		case 3:
			guiTexture.texture = health3;
		break;
				
		case 2:
			guiTexture.texture = health2;
		break;
		
		case 1:
			guiTexture.texture = health1;
		break;
			
		case 0:
			//gameover script here
		break;
	}
}