At 12:58 a.m. on April 16, 2013, while the nation was reeling from the Boston Marathon bombings only hours earlier, an unknown number of suspects assaulted the Metcalf Transmission Substation in Santa Clara County, California, which feeds power to Silicon Valley. The attackers initially used heavy wire cutters to snip fiber-optic cables operated by AT&T in a below-ground bunker. The team briefly disabled the 911 emergency system and phone lines. The suspects knew the specific manholes to open to reach the right cables. They were “clearly knowledgeable” about the layout of the substation and its communication systems, said one federal official.
By 1:31 a.m., a surveillance camera pointed along a chain-link fence around the substation recorded a streak of light that investigators from the Santa Clara County Sheriff’s office determined was a signal from a waved flashlight. It was followed by the muzzle flash of rifles and sparks from bullets hitting the fence. Additionally, following the attack, investigators found small piles of rocks near to where the shots had been fired, the type of formations that can be used to scout firing positions.
Jon Wellinghoff, chairman of the Federal Energy Regulatory Commission at the time, called it “the most significant incident of domestic terrorism involving the U.S. power grid that has ever occurred.” High-ranking government sources have told NBC they believe it was a trial run for a larger attack on the grid.
Officials say the attackers used night-vision scopes on their weapons and fired 120 rounds from high-powered rifles targeting transformers, which began to leak tens of thousands of gallons of oil and then overheated and shut down. The attack destroyed 17 large transformers. While some nearby neighborhoods temporarily lost power, “the big users weren’t even aware Metcalf had happened”, according to the Electric Power Research Institute. However, it took 27 days to repair the damage and cost over $15 million.
