Around 2:45 a.m. Wednesday morning, Seattle Police responded to the intersection of Harvard Avenue E and Lakeview Boulevard. E, just to the east of I-5, for a single car that had rolled over.
Firefighters extricated a woman in her 20s who was taken to Harborview Medical Center in critical condition.
Two other people were ejected from the car and were declared dead at the scene, police said.
Witnesses say they had previously been at the same party as the victims, and that for some reason the car accelerated and lost control before hitting a fire hydrant and rolling onto its top. Police said the car was badly damage, and debris crowded the road.
Roads in the area will be closed for several hours while police investigate the accident.