"The widely reported bright objects in the sky were debris from a Falcon 9 rocket 2nd stage that did not successfully have a deorbit burn," the service said in a tweet about the astral occurrence that the Seattle Times reported was seen shortly after 9 p.m.
There were no reports of damage or other impacts on the ground.
The rocket delivered Starlink satellites, built in Redmond, Washington, into orbit earlier this week, the Times reported.
SpaceX said Wednesday that the Falcon 9's first stage returned to Earth and landed as planned on its ocean-going barge off the coast of Florida.
MORE | Apparent meteor seen on video flashes across SoCal night sky
MORE | Bright light in sky caught on camera in Camarillo
MORE | SpaceX Mars prototype rocket nails landing, but then explodes
