Coach Deion Sanders had no update after the game other than to say, the "first thing I heard is he's going to be out a few weeks." Hunter was taken to the hospital during the third quarter for an evaluation.
Sanders did not offer specifics about Hunter's injury.
"The bad thing about losing Travis," said defensive back Shilo Sanders, "it's like you're losing two players at once."
Hunter absorbed an illegal hit to his midsection in the second quarter on an incompletion at the Colorado sideline. Colorado State was whistled for two fouls on the play: Nickelback Ayden Hector was flagged for pass interference, and safety Henry Blackburn was assessed a foul for unsportsmanlike conduct after a late hit out of bounds.
Hunter, who earlier coughed up a fumble that was returned for a touchdown, returned to the game, playing on both offense and defense through the second quarter.
The Buffaloes trailed the Rams 21-14 when Hunter was transported to the hospital but rallied for their third straight win.
Along with Buffaloes quarterback Shedeur Sanders, Hunter has been mentioned as an early candidate for the Heisman Trophy after playing both cornerback and wide receiver.
Information from The Associated Press was used in this report.