Buffalo Bills defensive back Damar Hamlin remained in critical condition on Tuesday after he went into cardiac arrest during a prime-time N.F.L. game, a frightening reminder of the ever-present risk of serious injury in America’s biggest sport that has the league facing one of its worst crises in decades.
Hamlin’s injury, following what looked like a routine tackle, has the N.F.L. again answering questions about player safety in a season marred by high-profile injuries.
With millions of fans watching on television, Hamlin, 24, collapsed in the first quarter of a crucial matchup with playoff implications on Monday night, forcing the league to suspend the game.