CSU's Henry Blackburn Receiving Death Threats After Travis Hunter Hit

Colorado State defensive back Henry Blackburn is on the receiving end of death threats after laying a controversial hit on Travis Hunter during Saturday's game ... and now, university police tell TMZ Sports an investigation into the hateful messages is underway.

Blackburn received a ton of heat for his massive late hit on the Colorado receiver in the first half of the Rams vs. Buffaloes matchup... which left Hunter sidelined for weeks with a lacerated liver.

Some looked at Blackburn's tackle as targeting ... including LeBron James, who went on X to say, "That was blatant and uncalled for IMO!"

Shortly after the tackle went viral on social media, the safety and his family were singled out by furious fans ... and we're told cops are taking the interactions seriously.

"CSUPD is aware of death threats against CSU football player Henry Blackburn, and the investigation is ongoing," a university police spokesperson told us on Monday.

"The police department will continue to monitor the situation, and the university is actively supporting the player and his family."

CSUI athletic director Joe Parker told Pete Thamel of ESPN he's concerned for Blackburn ... saying Henry never meant to hurt Hunter or anyone on the field.

"It's not what we teach or coach," Parker said. "We hope that the irrational vitriol directed at Henry stops immediately."