There's water coming up through the sidewalk!

Basia woke me up this morning at 7:00 as she was leaving for work. She says "There's water coming up through the sidewalk, next to the back porch".
So I got up and checked. Yup, it has to be a water pipe under there with a hole in it. The trouble is, as far as I know, there aren't any pipes under that particular spot. Where I know there's pipes, there's no water and where I see the water, there's no pipes (none that I know of anyway).
So, I filled a bunch of water jugs, in case this takes a while, and went back to bed. I'm not going to make a bunch of noise early on Sunday morning. Besides, Home Depot isn't open this early and I need to buy a sledge hammer to bust through that sidewalk. (besides the fact -- I just want to go back to sleep).
Later, I bought a sledge hammer and busted a hole in the sidewalk.

What I found was, the water was coming from the next section of sidewalk.
So, should I bust up another section of sidewalk? I told this problem to a coworker. Turns out he had busted several holes in the slab in his home before he called a plumber with a leak locater who pinpointed it several feet from where he was looking. I think I'll take his advice.