(Portland, OR)  --  Police are searching for a suspect in connection to a stabbing that seriously injured a man after the Waterfront fireworks show downtown Wednesday night.  Police say witnesses flagged down officers near Southwest 2nd Avenue and Stark Street after the stabbing at around 10:45.  Witnesses told police the suspect was accompanied by another man, and he used what appeared to be a long kitchen knife.  Police say it doesn't appear the suspect knew the victim.