SAVE button modal loading

I have a web form that the user fills it, and then clicks on the "SAVE" button.
So while the the application is processing the request on the server, the user waits until it is complete.

The problem is the user is clicking again on the SAVE button and it's saving data twice in the database.

So I need to "block" the screen, after the user clicks on the SAVE button and I want to place a modal loading while the server is processing.