Chicago police are investigating a spate of overnight violence that left two men dead and two others seriously wounded across the city late Friday and early Saturday. On the Far South Side, officers responding just before 10 p.m. found a 23-year-old man with a gunshot wound to the head inside a vehicle in the 11300 block of South Avenue G. He was taken to the University of Chicago Medical Center, where he died. A firearm was recovered at the scene, and Area Two detectives are handling the case. Roughly five hours later, two men sitting in a vehicle on the West Side were shot and taken to hospital in serious condition, according to preliminary police reports. Investigators have not released details on a motive or any suspects. Separately, a 22-year-old pedestrian was struck and killed by a northbound gray vehicle that ran a traffic signal around 3:30 a.m. in the 5400 block of South Kedzie Avenue in Gage Park. The driver fled, and no arrests had been made as of Saturday morning. Police have not said whether any of the incidents are connected.