This happened to us once about 5 years ago when my wife called me at work and said the washer was overflowing and there was no way to turn it off. And our house was built in 1958, so to put a full size washer and dryer in, the water supply had to originate from behind the refrigerator. So while the water was running my wife could not move the refrigerator to get to the shutoff valves. I was miles away and couldn't leave, so by the time, she was able to find someone to shut it off, we had 2-3 inches of water in the family room. It took hours of shopvac and days with a fan to dry it up.
So to end this amazingly boring post, I want everyone to check their dryer vent and washing machine hoses right now. A bit of preventative maintenance may save you hundreds of dollars, or even your life...