I had this happen and was laying on the floor getting to watch the whole thing play out.
Was filling an extra large garbage can for mixing up some salt water for the reef tank when while in my livingroom, my back went out and as I lay there on the floor not able to move, got to watch my kitchen fill, then the livingroom and eventually go out the open front door.
Only took about 30 minutes to eventually get myself up and make it to the hose shutoff. Luckily it was a nice sunny day, so the carpet was taken outside by some neighbors and they gave me some help cleaning up. My dog at the time enjoyed the mini tubby we had and I was pretty relieved I didn't get to add the salt before the flooding started.