Php Json获取内部数组

This is My json How can get "download" string

{
"total": 1,
"items": [
 {
  "id": "1186e1472bc1c",
  "title": "title,
  "desc": "",
  "download": "www.google.com",
   }
  ]
}

This is My code:

$response = file_get_contents($nagu);
$obj = json_decode($response, true);
$download = $obj ['items'];
echo $download;

I want output "www.google.com".

$download = $obj ['items'][0]['download'];
echo $download;