Step 1. Shut off the main water valve
Every minute the main stays open, more water enters your house. In most Kansas City homes, the main shut-off is in the basement on the wall facing the street, usually near where the water line comes in by the meter. In homes without basements, check the crawl space, the garage, or a utility closet. Turn it clockwise until it stops. If the valve is stuck or spins without doing anything, the valve itself has failed, and that's important information for whoever comes out.
Step 2. Drain what's left in the lines
The pipes are still full even after the main is off. Open the lowest faucet in the house, usually a basement sink or the tub on the lowest floor, and let the water run out there instead of through your ceiling. Flushing a toilet once helps too. This takes pressure off the break and can cut the leaking to a trickle within a couple of minutes.
Step 3. Respect the electricity
Water and wiring share your walls. If water is anywhere near outlets, light fixtures, or your electrical panel, don't wade in and don't touch the panel. If the affected area has its own breaker and you can reach the panel with dry hands on dry ground, turn that circuit off. If you can't do it safely, leave it alone and say so when you call for help. No floor is worth electrocution.
Step 4. Protect what you can and document everything
Move furniture, rugs, and anything valuable out of the water's path. Towels and buckets under active drips, trash bags over what can't move. Then take photos and video of everything: the water, the damage, the source if you can see it. Your insurance company will want documentation, and photos from the first hour are worth more than a written description from three days later.
Step 5. Make the call
This is the part most articles get vague about, so here's the honest version. A burst supply pipe usually needs two kinds of help: someone to stop the damage tonight, and a licensed plumber to replace the failed pipe. Ken answers 816-616-0993 at 2am, shows up, gets the water fully controlled, pulls soaked materials before they turn into a mold problem, and gets your home stable and safe. When the pipe itself needs a licensed plumber, he'll tell you straight and help you get the right one out, and the drywall, trim, and finish repairs after the plumbing is fixed are exactly his lane.
Why pipes burst in Kansas City, and how to not do this twice
Our winters do it. When temperatures dive, pipes in exterior walls, crawl spaces, and garages freeze, and frozen water expands until something gives. Three things prevent most middle-of-the-night calls: know where your main shut-off is before you need it, disconnect hoses and cover hose bibs every fall, and insulate any pipe that runs through an unheated space. If you don't know where your shut-off valve is, go find it this week. Tonight-you will thank you.