Why did an ordinary train ride turn into a nightmare for passengers in Chicago?br br Authorities were called to a train station in Forest Park, a village in Cook County, at around 5:30 a.m. on Monday. The shooting occurred on a Chicago Transit Authority (CTA) Blue Line train.br br Three people were pronounced dead on the scene, while the fourth victim died at a local hospital. Forest Park Police Department deputy chief Chris Chin told reporters that no additional information about the victims is known at the time.br br According to FOX 32 Chicago, a suspect fled the scene but was eventually arrested by authorities.