It's an attack on the MetroLink that's gone viral online, and the victim, police say, was a security guard.
Police said a 22-year-old woman was beating up a security guard who asked to see her ticket to ride the train at the North Hanley MetroLink stop Monday morning at around 7.
Don Carter said he was on the platform when he first heard what he thought was just an argument, but soon realized the guard-versus-passenger interaction was getting physical.
Carter recorded the attack and posted it on social media.
Metro Public Safety investigators say they made a positive ID of the suspect and have taken Ronisha Pampkin of St. Louis into custody.
A warrant has been issued for a charge of third-degree assault against Pampkin. Police say that charge could change, depending on the severity of the victim's injuries. She's being held on a $10,000 cash-only bond.
Metro contracts security for transit through St. Louis County Police and the agency says it will review security plans and staffing levels.
But the man who shot this now viral video says it doesn't show what most rides are like.
"I feel comfortable," Carter said "I feel somewhere I can be safe. The bus drivers are nice. Things happen. It was early in the morning and she wasn't feeling it. They got in a disagreement."