It works in the short term too. If a store only has 500 gallons of gasoline, does it sell it to the first customers who come along? If consumers fear a shortage, people could start hoarding by filling up their tanks. If the price remains the same as prior to the disaster, the store quickly runs out of fuel. Then no fuel will be available at any price. Also, those who filled up before the store ran out would be in a position to sell fuel from their gas tanks on the black market.
The store can always limit the amount a customer can buy. There are pluses and minuses to the market approach in an emergency. At this point in our economic development, it's ideal to have large players like Home Depot and Walmart who have the logistics to bring in extra supply at near normal prices.
Sometimes you may still need someone to drive a 100 miles away and bring in needed items. In the case it's OK to charge an extra high price and most gouging laws I've seen account for that.