The first call to police was for a shooting in the parking lot of the Hard Rock Café at Union Station just after 1:30 p.m.
Responding officers discovered the shooting actually happened on the sidewalk at 18th and Clark, near the exit of the Union Station Metro train stop.
The shooting victim's brother flagged down a driver, police said. The driver did what he could to help and gave the men a ride to a hospital.
Investigators thought it strange that there were no reports of gunfire. No one reported seeing or hearing anything out of the ordinary at a busy, public place on a weekday afternoon one block from Scottrade Center, hours before a Blues hockey game.
There was no suspect description and no word on a motive. It did not appear to have been a random attack, police said.
"Apparently, they (the victim and the shooter) were on the train earlier," said St. Louis Police Lt. John Green. "There was an argument with some other people. They got off at the 18th Street station. So I don't know if that had something to do with it or not…we have no witnesses to the incident except for the ones that were with him at the hospital. There are cameras in the area so we're going to take a look at all of the video surveillance."
The victim was a man in his early 20s, Green said. Police did not release his name.
There is a reward in the case. You can contact CrimeStoppers online or by calling 866-371-TIPS if you have information leading to an arrest. You do not have to leave your name to get the reward.