I was pretty surprised to find him still alive in the morning so with a little advice/help from friends, I was off to the store for a milk replacement while Equestrian Girl went to her job. A couple hours later he was well fed and doing fairly well.
Almost exactly 24 hours after finding the first mouse, Scott was back in telling us there were two more on the floor. Apparently the word got out that we had good milk and a warm bed. All three got moved to a larger container after having their share of milk from a tiny syringe. They made it through the night and were doing well the next day with two of them opening their eyes!
And then they weren't. Sunday morning I got up to find one had already crossed over the rainbow bridge and one was close. By the time Equestrian Girl got up, the third was was fading fast and passed in her hands... It was so sad to see them go like that after doing so amazingly well at first! Rest in peace little mice.