Police said investigators are working to find his killer after gathering evidence at the scene.
Police said the 46-year-old man was standing near the entrance doors in the 100-block of W. 79th Street around 3:30 p.m. when someone approached from the street and started firing.
The victim was shot in the chest and was taken to the University of Chicago Medical Center where he was pronounced dead, officials said.
Investigators spent hours assessing the scene. Evidence markers were placed near what looked like shell casings.
"I feel very upset. But you know why? People was trying to go home, go to work," said CTA rider Dwayne Marshall. "We need this route. I don't understand why people are just doing this crime...but it needs to stop it."
CTA riders who saw the aftermath of the shooting said this is a scene they've seen too many times.
"You need to go somewhere else with this? Because you got people that need to go to work. Come home and deal with the children," Marshall said.
No one is in custody and area detectives are investigating.
Red Line trains are still running, but are not stopping at 79th as police continue the investigation.