Horrifying moment during the Bills vs. Bengals game on "Monday Night Football" -- Buffalo safety Damar Hamlin collapsed at the end of a play ... and required CPR in the middle of the field.
The incident happened just minutes into the game's first quarter ... right after Hamlin tackled Tee Higgins to the ground.
The 24-year-old -- a sixth-round pick in the 2021 NFL Draft -- appeared to get up from the stop just fine ... but he seemed to lose consciousness as he got to his feet, and crumpled to the ground.