Crews were on their way to the Sumner substation about 7:20 p.m., and had not yet determined what caused the outage, spokeswoman Abigail Elliott said.
Residents in the areas of Algona, Auburn, Bonney Lake, Pacific, Sumner and Lake Tapps appeared to be affected.
The outage was affecting a transmission line to the company’s Sumner substation.
Crews expected to have power back about 11 p.m., but would know more once they got on scene, Elliott said.
Further details were not immediately available. Check back for updates.