ST. LOUIS — "It's scary to think that this would happen in a station like this where it's really business," said a concerned woman, who asked that her identity be released.
Witnesses told police in mid-afternoon Monday a mask and hoodie-wearing, young guy stormed through the front entrance at the St. Louis Gateway Transportation Center at south 15th and Poplar Streets near Enterprise Center.
Within moments witnesses said the gunman shot a teenage boy in his head and killed him.
Police say the boy was sitting in the lobby.
"It was just so crazy. We saw the young man's body just lying there on the floor. That could have been one of my family members. It's just sickening," the woman told 5 On Your Side's Robert Townsend.
Multiple police officers rushed to the scene, put up crime scene tape and started talking to witnesses.
The station was packed with dozens of travelers at the time.
The woman, who spoke with 5 On Your Side, says her brother was trying to buy a train ticket just minutes before.
She asked that her name not be revealed.
"The witnesses said the young man who was murdered was sitting in a seat in the lobby. The guy came in the building, stood behind him and said 'what's up now,' pulled a revolver out of his pants and shot him" said the woman.
Greyhound and Amtrak operate out of the station.
Customers say ticket counters for both companies temporarily shut down after the deadly shooting.
It happened after a violent weekend in St. Louis.
Police say early Saturday morning two innocent people were caught in the crossfire when hundreds of gunshots were fired near north 21st Street.
Back at the St. Louis Gateway Transportation Center a frustrated Jhordy Sanchez couldn't buy a bus ticket to Columbia.
"I'm just going to go to the airport and catch a shuttle bus. This is such a big inconvenience It's bad publicity for Greyhound and bad publicity for St. Louis," said Sanchez.
Nobody else was hurt.
Police quickly took a teenager into custody thanks to eagle-eyed witnesses.
"These people were very helpful that when they saw that, they remembered and provided us with a lot of information," said Major Ryan Cousins with the Metropolitan St. Louis Police Department.
However, that's little comfort for this weary woman.
"I'm tired of the violence and I'm ready to get my family out of town and move," she said.
Hours after the shooting, both Greyhound and Amtrak were once again selling tickets and running again.