Damar Hamlin: American Football player seriously injured in game collision

This video contains distressing images

Dozens of fans held an overnight vigil outside the stadium, as US Correspondent Robert Moore reports

There is shock in the world of US sports this morning after a devastating injury to a highly-regarded young American football player, Damar Hamlin.

It occurred during Monday Night Football - a hugely-popular weekly sporting occasion the US - during a game between the Buffalo Bills and Cincinnati Bengals.

Hamlin - a 24-year-old safety for the Bills - collided with another player in what appeared to be a freak accident, and after briefly getting up, he then collapsed in the field.

It was immediately apparent just how serious the injury was.

Medical teams and an ambulance came onto the field and engaged in CPR, and many of his teammates were in tears.

Players and coaches from both teams circled around on the field, and knelt in prayer.Hamlin was taken to hospital in Cincinnati where his condition is described as critical. It later emerged that he had suffered a cardiac arrest during the game.

It puts the spotlight back onto the safety of the NFL and of American football at all levels.

There has long been an animated debate and considerable controversy about whether the sport has sufficiently addressed the health of players, and especially the risk of concussion.

Across the sport and around the country, players expressed their shock and hopes that Hamlin would recover.

This may prove to be a moment of reckoning for American football as people evaluate both the dangers and the vast popularity - and big money - that flows from the game.