How to Display Custom Post Type's Gallery (images ) in Through WP_Query

Question

I am trying to load an Image Slider images from a Custom Post Type image Gallery Feature. For example let say I have an Custom Post Type called banner which I can load images to it's Gallery and I have an HTML code like this:

<div class="item active">
  <img src="assets/img/ban1r.jpg" alt="">
  <div class="carousel-caption">
    slide 1
  </div>
</div>

<div class="item active">
  <img src="assets/img/ban2r.jpg" alt="">
  <div class="carousel-caption">
    slide 1
  </div>
</div>

Can you please let me know how I can use the custom WP_Query to retrive the images from the custom post and load them into slider instead of above HTML?

So far I have done something like this but it is not displaying any image!

<?php
$args = array( 'post_type' => 'banner');
$loop = new WP_Query( $args );
while ( $loop->have_posts() ) : $loop->the_post();
    $gallery = get_post_gallery_images($post);
foreach( $gallery as $image ) {
       echo '<div class="item active">';
       echo '<img src="' . $image . '">';
       echo '</div>';
    }
endwhile;
?>

Update: The Result of var_dump($POST)