Display images from certain page only

How should this code be adapted to only display images that held in a gallery on page id 2940?

<?php

$query = new WP_Query(array(
'post_type' => 'page',
'posts_per_page' => 4,
'paged' => 1,
'orderby'=> rand,
) );
// WP Tiles arguments
$args = array(
'grids' => plain,
'images_only' => true,
'link'            => 'none' //post|thickbox|attachment|none

);
// Display the tiles
the_wp_tiles( $query, $args );
?>

Thanks

https://wordpress.org/plugins/wp-tiles/