(Portland, OR)  --  Portland police are investigating a single-vehicle crash that killed one person and injured two.  Authorities say a car traveled off the roadway on Skyline Boulevard shortly before eight o'clock last night, and rolled down a 150-foot embankment toward Meridian Ridge Drive.  Police say the car hit a house on the way down and caught fire.  A man was found dead at the scene, and another man and a woman are being treated for traumatic injuries.