Step one
Limit the water if it is safe to do so
Closing the main shutoff limits how much more water enters the property. Do it only if you already know where the valve is and can get to it without stepping into standing water. If you cannot, leave it and tell the office the water is still on.
For an overflowing toilet or drain, stop using that fixture. Flushing again to see whether it clears can push more wastewater out. Get people and pets clear first; cleanup can wait.
