Stuck on "Saving world" screen

I tried exiting my world and it is now stuck on the "Saving world"screen.
I can't close Minecraft, because it ignores pressing the button inputs, pressing x and even alt f4!
The computer does not say anything about the game not reacting.
It's like it learned to resist the users commands like a Terminator movie!

I have not tried restarting my pc yet, as I thought it would be handy to let some people know.