Bomberman like explosion

Hi I bet everyone here knows what bomberman is, ok, so I am making a game like bomberman but I don't know how could I achieve the same type of explosion, for now I created a bomb that maes 4 raycasts, for the 4 diferent directions, and if it is on range it will send the message to explode. So, this explosion type is working, but could be better, in bomberman a explosion lasts like 0.5 seconds, and not just the explosion moment, and I wanted to achieve that, but with the script that I currently have, if it lasts 0,5 seconds it will just go on and destroy everything in it's max range ( if the first cube is on range is destroyed, and if it finds another cube in the same line within the raycast range is also destroyed, and not only the first one), also, this game made in unty shows a explosion like in bomberman, I wonder if the explosion is made by instantiating colliders according to max range, or if it's a raycast, and also, what I wanted to know is how do I make those kind of explosions effect? is that particles is that a texture?

here's my current bomb script:

 #pragma strict
 
 var fire : float = 3;
 var timer : float = 3.3;
 var damage : int = 1;
 var hasReceived : boolean;
 
 var distance1 : float;
 var distance2 : float;
 var distance3 : float;
 var distance4 : float;
 
 function Update ()
 {
     timer -= Time.deltaTime * 1;
     if (timer <= 0)
     Explode ();
         
     if(GameObject.Find("Capsule").GetComponent(Player).fire == 1)
     fire = 2.90;
     
     if(GameObject.Find("Capsule").GetComponent(Player).fire == 2)
     fire = 4.90;
     
     if(GameObject.Find("Capsule").GetComponent(Player).fire == 3)
     fire = 6.90;
     
     if(GameObject.Find("Capsule").GetComponent(Player).fire == 4)
     fire = 8.90;
     
     if(GameObject.Find("Capsule").GetComponent(Player).fire == 5)
     fire = 10.90;
     
     if(GameObject.Find("Capsule").GetComponent(Player).fire == 6)
     fire = 12.90;
     
     if(GameObject.Find("Capsule").GetComponent(Player).fire == 7)
     fire = 14.90;
     
     if(GameObject.Find("Capsule").GetComponent(Player).fire == 8)
     fire = 16.90;
     
     if(GameObject.Find("Capsule").GetComponent(Player).fire == 9)
     fire = 18.90;
     
     if(GameObject.Find("Capsule").GetComponent(Player).fire == 10)
     fire = 20.90;
 }    
 
 function Explode ()    
 {
     hasReceived = true;    
     var Front : RaycastHit;
     var Back : RaycastHit;
     var Left : RaycastHit;
     var Right : RaycastHit;
         
     if(Physics.Raycast(transform.position, Vector3.forward, Front))
     {
         distance1 = Front.distance;
         if (distance1 < fire)
             {
             Front.transform.SendMessage("ApplyDamage", damage, SendMessageOptions.DontRequireReceiver);
             }            
     }
         
     if(Physics.Raycast(transform.position, Vector3.back, Back))
     {
         distance2 = Back.distance;
         if (distance2 < fire)
             {
             Back.transform.SendMessage("ApplyDamage", damage, SendMessageOptions.DontRequireReceiver);
             }    
     }
         
     if(Physics.Raycast(transform.position, Vector3.left, Left))
     {
         distance3 = Left.distance;
         if (distance3 < fire)
             {
             Left.transform.SendMessage("ApplyDamage", damage, SendMessageOptions.DontRequireReceiver);
             }    
     }
         
     if(Physics.Raycast(transform.position, Vector3.right, Right))
     {
         distance4 = Right.distance;
         if (distance4 < fire)
             {
             Right.transform.SendMessage("ApplyDamage", damage, SendMessageOptions.DontRequireReceiver);
             }            
     }
         
     yield WaitForSeconds (1);
     GameObject.Find("Capsule").GetComponent(Player).bombs += 1;
     Destroy(gameObject);    
 }
 
 function ApplyDamage ()
 {
     if (hasReceived == false)
     Explode ();
 }