CHICAGO – Police have detained two people for questioning after a man was murdered in the Hubbard Street nightlife district in River North early Saturday morning. Witnesses reported that the incident began as an argument between a group of people in the first block of West Hubbard Street, just east of Dearborn, around 3:43 a.m. The argument turned physical and escalated again when one man pulled out a gun and fired a shot, officials said.