Why my NPCs shoot the player but not other GameObjects?

Hi folks! I've been studying Unity and C# for a while now, but I'm having a hard headache with this problem. It looks like a bug, but it can be a scripting error (AKA myfault).

Can anyone figure out why, using this script, my NPCs do shoot at the Player when I type "Player" on targetTag, but don't shoot other NPCs? Even if I change the NPCs tag to Player, they won't do it!

If I wanted them to shoot the player, the script would be just fine: the only shoot when they have a clear line of sight and on a random basis...

using UnityEngine; using System.Collections;

public class FireRangedWeapon : MonoBehaviour {

 [SerializeField] private string targetTag;
 [SerializeField] private float power = 10.0f;
 [SerializeField] private float weaponRange = 20f;
 [SerializeField] private int minReloadTime;
 [SerializeField] private int maxReloadTime;

 private float reloadTime;
 private GameObject target;

 public GameObject projectile;


 void Start ()

 {
     StartCoroutine (Attack ());
 }


 IEnumerator Attack()
 {
     FindClosest ();
     if ((Vector3.Distance (transform.position, target.transform.position) <= weaponRange) && !Physics.Linecast(transform.position,target.transform.position,1))
     {
         transform.LookAt (target.transform);
         GameObject newProjectile = Instantiate(projectile, transform.position + transform.forward, transform.rotation) as GameObject;
         newProjectile.GetComponent<Rigidbody>().AddForce(transform.forward * power, ForceMode.VelocityChange);
     }

     reloadTime = Random.Range (minReloadTime, maxReloadTime);
     yield return new WaitForSeconds (reloadTime);
     StartCoroutine (Attack ());
 }
     
 void FindClosest()
 {
     GameObject[] gos;
     gos = GameObject.FindGameObjectsWithTag(targetTag);
     GameObject closest = null;
     float distance = Mathf.Infinity;
     Vector3 position = transform.position;
     foreach (GameObject go in gos) {
         Vector3 diff = go.transform.position - position;
         float curDistance = diff.sqrMagnitude;
         if (curDistance < distance) {
             closest = go;
             distance = curDistance;
         }
     }
     target = closest;
 }

}