Your house now may contain
Mud, sand, mold, gasoline, pcbs, asbastos, lead paint, prety much any bad crap that comes to mind.
You will need proper clothing just to inspect the house, boots, coveralls gloves, breathing filter. Take a camera with you.
Do not enter a building with obvious structural dammage until you are sure that it is safe to do so.
Turn off the gas at the meter.
Turning off the power is a little tricky. Standing in mud and turning off the main may be dangerous. Perhaps a dry piece of wood to get some distance.
Everything in the house that got wet is contaminated and needs to be removed. Salt water distroys electronics, fridge, stove, TV,
After removing all the mud and funiture and carpets,
Drywall and insulation must be removed well above the high tide marks on the wall and yes that includes behind kithcen cupboards.
Exterior doors are often packed with insulation around the frame and should be removed and allowed to dry, may be salvagable.
Rince everthing down with a hose when water is available and pressure washing is better if you can.
Hard wood floor a distroyed and should be removed sooner is better than later and lamminents need to go asap.
Just like a new house, this wants to stand open to dry out.