The female officer was not in uniform, and was sitting in the driver’s seat of the unmarked unit, about to go into a neighborhood meeting in the 2900 block of South Vernon Avenue in the Prairie Shores neighborhood when she was confronted about 6:30 p.m. Wednesday. It’s possible the officer wasn’t the first person the pair targeted Wednesday night, as a black pickup was used in an earlier armed robbery of two other women on the South Side, said Kellie Bartoli, a police spokeswoman.