Savannah-Chatham police are investigating a robbery Thursday that ended with a gunshot fired into the air at a crowded shopping center in the middle of the afternoon. Police responded to the food court at Savannah Mall on the 14000 block of Abercorn Street at about 1:54 p.m. where they found Nicholas Rivera, 28, who was reportedly robbed while attempting to sell a computer he advertised on Craigslist. The suspect reportedly grabbed the laptop and then ran out of the food court with Rivera trailing behind him. Once outside, Rivera fired a warning shot into the air, and the suspect dropped the computer.