Q: Safari update

I am waiting and waiting and waiting for my Macbook Pro, running El Capitan, to reboot after restarting during an update of Safari and Garage Band.  I have typed in my password on the normal start up screen, and can now only see my identity and avatar, a very dim and unfocused version of my desktop image, and a horizontal bar that is sloooowly filling in with white from the left to the right.  It has been at least two hours already.  I have tried to force the computer to close, and tried to restart, with the same result.  Any suggestions?