The Wednesday morning shootout on Interstate 75 outside of Cincinnati followed an altercation between members of T.I.'s crew and a group of men at the Club Ritz in Roselawn, Ohio, the Cincinnati Enquirer reported.
Witnesses told police the fight broke out after a member of T.I.'s posse began throwing money from the stage into the audience.
"It was supposed to be for the ladies," the witness said. "But it (the money) was hitting the guys in the face and they were like, 'We got money' so why are you throwing money at us?'"
T.I., whose real name is Clifford Harris, shepherded his group into their touring vans and took off -- but they were followed by four Cincinnati men in two sport utility vehicles, the newspaper said.
Police were soon called to the highway, where they found four members of T.I.'s entourage wounded by gunfire.
Killed was Philant Johnson, 26, a friend of the rapper as well as his personal assistant and an employee of Grand Hustle Records.
Two others were treated and released while Janice Gillespie, 21, was admitted to the University of Cincinnati Hospital and is in stable condition.
Police issued an appeal to witnesses in their efforts to find the shooters.