Actually the term would be "market manipulation". The front end supply and refineries were affected - but the likely culprits to higher prices are the commodities traders who bid up the prices, and maintain high prices to cover their investments. Charges of "price gouging" are legitimate, and various state Attorneys General are looking into reports of gouging. Keep in mind, the dealers had already purchased the gasoline they were selling, and they raised the prices arbitrarily.
Yes people panicked and hoarded, and bought more gasoline than normal. For many, gasoline is more or less a necessity - either one buys gas or one does not get to work. Now, in an emergency, people could have elected to 'carpool', assuming a person has made prior arrangements with a friend or colleague, or people could have used public transportation. But then one surrenders the freedom to come and go as one pleases.
A temporary and minor change in oil supply. Gas stations ran out of gas because the demand exceeded supply.
But, some of those gas stations who did not run out of gas, and who had ample supply, did raise prices - when there was no shortage.