I have this piece of code:

foreach (DynamicBuffer<Items> items in SystemAPI.Query<DynamicBuffer<Items>>())
{
   ...
}

I am trying to modify a specific element of items. This is how I am trying to achieve this:
items[3] = modifiedItem;

But I get the error Cannot modify members of 'items' because it is a 'foreach iteration variable'. How can I modify the elements of items?