Array Issue

I am trying to make an array of lights and when a specific event happens it turns them all off. I have the array working and if I place a debug statement in the loop for it it will print off just fine.

I cant figure out how to make it turn off all my lights.

 using UnityEngine;
 using System.Collections;
  
 
 public class DayNightController : MonoBehaviour
 {
 
 public GameObject[] lights;
 
 
 void Update ()
 {
 
 for(int i = 0; i < lights.Length; i++)
                 
     {
         lights.SetActive (false);
     }
 }
 
 
 }

I get this error : error CS1061: Type UnityEngine.GameObject[]' does not contain a definition for SetActive' and no extension method SetActive' of type UnityEngine.GameObject[]' could be found (are you missing a using directive or an assembly reference?)