Why dosen't querySelector work with getElementById? JS

Question

Why can't I get any element from getElementById when I try to use querySelector in my code?

let items = document.querySelector('.items');
let item1 = items.getElementById('item1');
let item2 = items.getElementById('item2');

console.log(items, item1, item2)

<div class="items">
  <div id="item1"></div>
  <div id="item2"></div>
</div>