A gunman with a military-grade assault rifle opened fire on a pickup basketball game in the Back of the Yards neighborhood late Thursday, injuring 13 people and dragging the city back into the international spotlight for its violent crime problem. At least 16 bullets were fired into Cornell Square Park around 10:15 p.m. on Thursday, wounding a 3-year-old boy and a dozen other people. All are expected to survive, many with wounds to their arms and legs. Shell casings found around the blood-soaked basketball courts were 7.62 mm rounds, which are traditionally used in AK-47 assault rifles and rarely found...