Newburgh — A 21-year-old man was stabbed by an unknown assailant after a Jadakiss concert at a local nightclub early this morning. The man was leaving 90 Broadway when he was stabbed multiple times, according to police. He was taken to St. Luke’s Hospital for treatment. Anyone who witnessed the incident or has any information is urged to call City of Newburgh detectives at 569-7509, or Det. Thomas Nafey at 569-7511.