If you come across a downed power line, stay as far away from it as you can and call Puget Sound Energy at 1-888-225-5773. Assume it is live. Never touch a downed power line or anything near it.
Do not drive over down power lines. Should a power line fall on your car when you're driving, slowly continue to move completely clear of it. If your car can't move away from the power line, stay in the car until help arrives.
If a person or pet comes in contact with a power line, stay clear and call 911 immediately. Do not touch them or the wire.
More information available here: https://www.pse.com/safety/ElectricSafety/Pages/Downed-Power-Lines.aspx