The crash happened just before 9 p.m. at Juanita Drive NE and NE 120th Street.
Police believe Kelly Hudson drifted into the wrong lane of traffic and slammed her minivan into a car carrying four people, killing 81-year-old passenger Joyce Parsons.
Police say their investigation revealed Hudson was likely intoxicated. She was taken to Evergreen Medical Center for treatment of minor injuries, then booked into the King County Jail for investigation of vehicular homicide.
The three other people in the car that was hit were taken to Harborview Medical Center in Seattle. An elderly man and woman were listed in critical condition while another elderly man was listed in serious condition.
Investigators say a witness behind Hudson's car was on the phone with 911 dispatchers reporting a "possible drunk driver" in the moments prior to the crash, and the witness was still on the line when the crash occurred.
Police closed a stretch of Juanita Drive for several hours while they collected evidence at the scene.