Fans gathered near the emergency room entrance with some of them holding candles.

The NFL has been dealing with growing concerns in recent years over concussion injuries of players.
The NFL has been dealing with growing concerns in recent years over concussion injuries of players. (Twitter/@buffalobills)

Athletes, celebrities and fans expressed their prayers and concerns on social media for Buffalo Bills defender Damar Hamlin after he collapsed out on the field during a game.

At Monday night's game against the Cincinnati Bengals, Hamlin took a hard hit to the chest as he tackled Tee Higgins during the first quarter of the match, stood up and then collapsed to the ground.

He received medical attention for more than 30 minutes before being taken from the field in an ambulance.

Since then, onlookers have been holding their breath to learn how Hamlin was doing, who is currently in critical condition.

READ MORE: NFL player Damar Hamlin in critical condition after hard tackle

Several NFL clubs, including the Dallas Cowboys, New York Giants, Seattle Seahawks, and Arizona Cardinals, tweeted prayers for Hamlin on Twitter. 

The NBA and the Boston Bruins of the NHL were among the other sporting organisations to take notice of his condition.

The NFL's official Twitter account shared the reactions of other NFL athletes who took to Twitter in order to share their well-wishes for the Hamlin after the tragic incident.

Former NFL player Robert Griffin III pleaded with his followers not to release the footage of Hamlin's crash and subsequent fall. Instead, Griffin requested that people spread a picture of several players kneeling on the field to pray for Hamlin.

NBA and LA Lakers star Lebron James also sent his prayers to Hamlin.

The Buffalo Bills' official Twitter account shared a photo of players kneeling to pray for their teammate.

Paycor Stadium — the Bengals' home venue and the scene of Monday's game — switched to using blue lights in honour of Hamlin and the Buffalo Bills.

Fans gathered for a vigil outside the medical facility where Hamlin was taken.

Hamlin was rushed to the University of Cincinnati Medical Center following the cardiac arrest he suffered on the field.
Hamlin was rushed to the University of Cincinnati Medical Center following the cardiac arrest he suffered on the field. (AFP)

Early Tuesday morning, the Buffalo Bills' Twitter account posted an update on Hamlin, saying that the player suffered a cardiac arrest on the field and remains in critical condition.

Four minutes after Hamlin passed out, an ambulance arrived on the scene with other players crying, including cornerback Tre'Davious White. Buffalo’s Josh Allen and Cincinnati’s Joe Burrow, both quarterbacks, hugged.

Allen tweeted: "Pray for our brother".

Source: AFP