While it was unclear how exactly the person may be connected to the case, a senior police official confirmed that the person of interest was being questioned by two detectives Wednesday afternoon. The Chicago police officer and two federal ATF agents were shot early Wednesday while working undercover, suffering non-life-threating injuries while entering I-57 in an unmarked vehicle in the city's Morgan Park neighborhood on the Far South Side, authorities said. The shooting took place at around 5:50 a.m. on the on-ramp of I-57 at the expressway's intersection with 119th Street, blocks away from the 22nd District police station, Chicago Police Supt. David Brown said at a news conference outside Advocate Christ Medical Center, where the officers were hospitalized.