The sound that wakes you up
It's usually not a bang. It's a hiss, or a soft rushing noise somewhere behind a wall, or water already creeping across the kitchen floor from under the sink. Maybe it's dripping through the ceiling below a bathroom. Whatever woke you up, the first few minutes matter more than anything else that happens that night.
In Nixa, a lot of this happens in winter when temperatures drop into the teens or lower and a pipe in an exterior wall or an unheated crawlspace finally gives out after freezing and thawing a few times. It also happens in older homes around town, the ones built in the 60s through 80s with galvanized steel supply lines that have been quietly corroding for decades. Either way, your job right now is not to figure out why. It's to stop the water.
Shut off the water before you do anything else
Every house has a main shutoff valve. In most Nixa homes it's where the water line enters the house, often in the basement, a crawlspace access area, or a utility closet near the water heater. Some newer builds on the south side of town have it in an exterior pit near the street. Find this valve now, while everything is calm, not at two in the morning with a flashlight in your teeth.
Turn it clockwise until it stops. If it's a gate valve that's been sitting unused for twenty years, it may be stiff or even seized. Don't force it hard enough to snap the stem. If it won't budge, move to the next option.
If you can isolate the leak to one fixture, like a washing machine line or a bathroom sink, there's often a smaller shutoff valve right at that fixture. Turning that off may be faster and spares you from cutting water to the whole house in January, which matters if you've got a water heater or humidifier that doesn't like being without flow.
More on this from What To Shut Off First When A Pipe Lets Go At Night.
Kill the power to anything near the water
Water and electricity sharing space is the bigger danger than the water damage itself. If the leak is near an outlet, a light fixture, or the electrical panel, and you can reach your breaker box safely without stepping through standing water, shut off power to that circuit or the whole panel. If the panel itself is wet or you'd have to walk through water to get to it, stay out and wait for someone qualified. No amount of carpet is worth getting shocked over.
What to check while you wait it out
Once the water's off, look at where it's pooling and whether it's moving toward anything that will hold a lot of damage, hardwood floors, drywall, a finished basement. Towels and buckets buy you time, they don't fix anything. If you've got a sump pump and the leak is in the basement, make sure it's running and the discharge line outside isn't frozen shut, which happens often enough here during a hard cold snap.
Check your water heater and furnace if they're in the same area. Both can be damaged by even a couple inches of standing water, and a furnace that short-circuits in January is its own emergency.
If the leak came from a frozen pipe, don't try to thaw it yourself with an open flame or a torch. People have started house fires doing exactly that. A hair dryer on a low setting, applied slowly, is about as aggressive as you should get, and only after the water's shut off.
When it's past what you can handle
If you can't find the main shutoff, if it won't turn, if the water's coming from inside a wall or ceiling with no visible source, or if there's any standing water anywhere near the electrical panel, that's the point to call an emergency plumber rather than keep troubleshooting. A burst pipe at night in Nixa, especially during a freeze, isn't something that waits politely until morning. The ground is already cold, more pipes may be close to failing the same way, and a few hours of water running unchecked into a crawlspace or slab foundation turns a one-fixture repair into a much bigger job.
A frozen or split pipe in a wall usually means a section of pipe needs to be cut out and replaced, sometimes requiring the wall to be opened. That's not a weekend project with a hardware store pipe wrench. It's a job for someone who can also check the rest of your system for pipes that are about to go the same way, especially if your house still has its original plumbing from decades back.