(Portland, OR)  --  An investigation is underway into the deadly officer-involved shooting of a suspect accused of stabbing four people in southeast Portland.  Police say officers responded to a home on Southeast Center Street yesterday morning to find the male suspect holding a woman at knifepoint.  Officers opened fire, and the man was pronounced dead at the scene.  Police say the suspect had stabbed and seriously injured three men and a woman before officers shot him.  It's not yet clear what led to the stabbings, but police say all four victims and the suspect knew each other.