At about 1:00 a.m. on April 16, 2013, snipers hit and knocked out 17 transformers in 19 minutes at the Pacific Gas & Electric's Metcalf power transmission station near San Jose, Calif. This illustrates a nightmare scenario for electric utilities: A physical or cyber attack that disrupts power transmission.
More and more utilities are bringing in engineers to examine the electrical grid's vulnerabilities to attacks.