Do These Things While Help Is Coming
Close the main shut-off first. If the house valve is stuck or missing, the curb stop out by the street can cut the supply, but it often needs a curb key. Next head to the panel, but only if you can get there on dry footing.
Standing water and live outlets are the biggest danger on these calls. If the water has reached outlets, extension cords or electronics, keep out of the room and let the dispatcher know. Get papers, medications and valuables up and off the floor.
Dispatcher tip: Tenant with a landlord who is not answering? Close the valve, photograph everything, and send a timestamped text and email so it is clear you moved fast.