Extensive cyber attack and the psychological consequences?

One often raised question when talking about cyber attacks is what can possibly the damage be. Many people often argument using examples as commercial ventures such as Amazon on Ebay, arguing that if they are victims of cyber attack they will probably just be down for the day, and customers will purchase and trade whatever they intended the next day. However, what if for example someone managed to launch an attack that would take off the whole electrical grid of a major city. Nowadays even those can be accessed remotely, and many use a bit old systems that can be penetrated with some effort. With the result of power shortage for 1 single day, and many experts argue that a sophisticated attack might make a damage that would take as long as 6 months to repair. Leaving a major town with more than 1 million people without electrical power would cause chaos, resulting psychological traumas in both the people that live there but also in the whole country. It is often said that the best political weapon is the weapon of terror, making people afraid, which is exactly what happened on 9/11. Its not the number of casualties, but inflicting psychological trauma and fear in the rest of the population.