Three power substations in East Pierce County operated by Tacoma Public Utilities and Puget Sound Energy were attacked and vandalized early Sunday, resulting in power outages affecting thousands of customers. The affected area was centered in Graham.
The attacks were preceded by a warning from federal law enforcement citing a possible threat to the local electrical grid, according to a statement from TPU. The utility did not describe the specific nature of the attack, apart from saying it occurred early Sunday morning. According to the Pierce County Sheriff's office, unknown individuals broke into the two substations and vandalized equipment.
The sheriff's office reported that a third substation on South Hill, operated by Puget Sound Energy, was also attacked earlier Sunday.
All three incidents were described as burglaries, but nothing was taken, said sheriff's spokesperson Darren Moss in an emailed statement.
TPU released a statement Sunday afternoon providing additional information.
"Earlier this month, we were alerted by federal law enforcement of a security alert for the electrical grid. Tacoma Power follows federal reliability standards, including assessing physical risks to our critical energy infrastructure and applying recommended mitigation measures. In accordance with best practices, we do not share the details of our resiliency and security tactics.
"The investigation into today's incidents is ongoing, and therefore we cannot provide any further details about the incidents to allow law enforcement time to do their job."
It is not clear whether the incident is linked to similar recent incidents in Washington and Oregon that affected six substations, including two operated by Puget Sound Energy.
"At this time deputies are conducting the initial investigation. We do not have any suspects in custody," Moss's statement said. "It is unknown if there are any motives or if this was a coordinated attack on the power systems."
