Skokie police responded to the Dempster Swift Station located at 5005 Dempster Street around 6:50 p.m.
The preliminary investigation suggests that an adult pedestrian crossed the tracks and was struck by a passing train, police said. All signal devices were properly functioning at the time, officials added.
The North Regional Major Crimes Task Force and Major Crash Assist Team are assisting Skokie police with the investigation.
Service on the CTA Yellow Line was suspended for the rest of the night, and a shuttle bus was running, transit officials said.
The CTA said it appears to be an accident.