How do you interact with background button?

[Oba22]

There's a group of buttons. I need the button to change the color of the button and remain so until the user presses another button.

Now I tried to do it with mousedown and mouseup, but it didn't help. The color of the button changes for a few seconds and returns to the old state.

$(function() {
    $('.btn').on('mousedown', function() {
        $(this).addClass('down');
    });
    $('.btn').on('mouseup', function() {
        $(this).removeClass('down');
    });
});

.down {
  background: red;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
выберите что-то одно
<div class="btns">
  <button class="btn">Тест1</button>
  <button class="btn">тест 2</button>
  <button class="btn">тест 3</button>
  <button class="btn">тест 4</button>
</div>

[charlenef]

$(function() {
  $('.btns .btn').on('click', function() {
    $(this).closest('.btns').find('.btn.down').removeClass('down');
    $(this).addClass('down');
  });
});

.down {
  background: red;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
выберите что-то одно
<div class="btns">
  <button class="btn">Тест1</button>
  <button class="btn">тест 2</button>
  <button class="btn">тест 3</button>
  <button class="btn">тест 4</button>
</div>