Could San Diego Black thursday was a terrorist's attack?

According SDG&E, due to the Nuclear Power Plant at San Onofre turned off its system automatically when there's an incoming potential threat, and therefore that current was distributed elsewhere and caused the biggest blackout in history.

First of all, I doubted that one single person can caused such damage in this age of technology. Second is why did the nuclear power plant automatically shut off, plus if they can do this then why the power company could not. Another clue is that it happened 30 minutes prior to President Obama address the nation.

I don't believed that we are being told the truth.