Select/attack closest target array

Hey Guys,

I have a horde of Zombies (of course) that are attacking a group of towers, each tagged "Tower". The script works okay, but I want the zombies to attack the closest building first, then the next closest, and so on. I'm sure I need an array to do t$$anonymous$$s, but have little experience. Here's my code thus far:

 using UnityEngine;
 using System.Collections;
 
 public class EnemyAI : MonoBehaviour {
     public Transform target;
     public int moveSpeed;
     public int rotationSpeed;
     public float maxDistance = .5f;
 
     private Transform myTransform;
     NavMeshAgent agent;
 
 
     void Awake () {
         myTransform = transform;
     }
 
 
     void Start () {
         agent = GetComponent<NavMeshAgent> ();
 
     }
     
 
     void Update () {
 
         GameObject go = GameObject.FindGameObjectWithTag("Tower");
         
         target = go.transform;
         Debug.DrawLine(target.position, myTransform.position, Color.yellow);
 
         //Look at Target
         myTransform.rotation = Quaternion.Slerp(myTransform.rotation, Quaternion.LookRotation(target.position - myTransform.position), rotationSpeed * Time.deltaTime);
 
         if (Vector3.Distance(target.position, myTransform.position) > maxDistance) {
         //move towards Target
         myTransform.position += myTransform.forward * moveSpeed * Time.deltaTime;
     }
     }
 }

What would be the best way to add the array and make t$$anonymous$$s work?

Thanks,

Stef