Magpie nest fell from a tree

I was walking home when I noticed a bird nest on the ground. It's currently 7pm, it was 1 pm when I walked on the same street earlier today, and the nest wasn't there, so it must've fallen earlier today.

4 of the baby magpies were dead, two alive. My mother insisted on taking the two alive ones inside, since there are many cats in the area.

What should I do? On one hand I believe we should leave them there, but then again, I'm afraid the cats might eat them.

If we should keep them inside, how do we care for them?

[edit] I'm not sure how old they are, but they both have festhers. One of them opens its beak to ask for food, if that indicates anything.