The boy, whose name has not been released because he is a juvenile, got into a “verbal exchange” with the 60-year-old victim before shooting him on the bus in south-west Denver on January 27, police said in a statement.
A second person suffered minor injuries that did not require hospitalisation.
The suspect was arrested Thursday and was being held for investigation on suspicion of first-degree murder.
No other information was released, and the probable cause statement was not publicly available because the suspect is a minor.
