Damar Hamlin, who plays safety for the NFL’s Buffalo Bills, received CPR and was carted off the field in an ambulance on Monday night, after collapsing to the ground following a tackle against Cincinnati Bengals receiver Tee Higgins.
The hit came in the first quarter of the game in Cincinnati.
Mr Hamlin reportedly hit Mr Higgins on a play, stood to his feet, then crumpled to the ground.
First-responders rushed on field and administered CPR, before driving the injured safety away in an ambulance.
“Have never seen what’s happening in this Bengals-Bills game,” sports journalist Jemele Hill wrote on Twitter on Monday. “Player has been down for several minutes and is receiving CPR, according to the broadcast. This is truly terrifying. Praying for Damar Hamlin.”
Players on both the Bills and the Bengals could be seen kneeling, crying, standing near Mr Hamlin, and praying as the player received treatment.
This is a developing news story and will be updated with new information