【PHP】多次元配列の列のすべての値を合計する方法

以下のような多次元配列があります。

$array10 = array(
  array(
    "kill" => array(
      "zombie" => 10,
      "skeleton" => 15
    ),
    "killed" => array(
      "zombie" => 5,
      "skeleton" => 3
    )
  ),
  array(
    "kill" => array(
      "zombie" => 20,
      "skeleton" => 30
    ),
    "killed" => array(
      "zombie" => 10,
      "skeleton" => 6
    )
  )
);

killのzombie、killのskeleton及びkilledのzombie、killedのskeletonそれぞれ項目別に合計する方法。

foreach ($array10 as $subArray) {
  foreach ($subArray as $key => $values) {
    foreach ($values as $id => $value) {
      $array11[$key][$id] += $value;
    }
  }
}