NFL player in 'critical condition' after collapsing on field

The medical emergency sparked an immediate outpouring of well-wishes from fans, commentators and other players, and brought attention back to the particularly dangerous nature of America's most popular sport.

Part-way through the first quarter of Monday night's matchup, Hamlin took a hard hit as he tackled the Bengals' Tee Higgins.

He then stood up and suddenly collapsed to the floor, with medical staff rushing onto the field.

Players from both NFL teams, clearly shaken by what they had witnessed, gathered around Hamlin during the treatment, which ESPN said included CPR, with many of them kneeling to pray and some openly weeping.

Hamlin "was then transported to a local hospital where he is in critical condition," the NFL said in a statement.

The crowd in Cincinnati remained silent and television coverage broke away from the scene on the field.

ESPN commentator Joe Buck said that medical staff had been "pounding" on Hamlin's chest and it was quickly clear from the reaction of the players that the situation was grave.

After the ambulance had left the field, reports initially suggested the game was going to restart following a five-minute warm-up, prompting an outpouring of anger on social media.

During ESPN's broadcast of the unfolding events, Booger McFarland, a former NFL player and analyst, also called for the league to abandon the game.

"Nobody is concerned about football right now... they are concerned about one thing, the health and safety of this young man," he said.

The two team's coaches conferred with referees, and players were then told to head to the locker room, while the game was announced "temporarily suspended."

The NFL then issued a statement saying that league commissioner Roger Goodell had announced the game had been postponed.

"The NFL has been in constant communication with the NFL Players Association which is in agreement with postponing the game," the statement concluded.

"Our thoughts are with Damar and the Buffalo Bills. We will provide more information as it becomes available," the NFL added.

'Terrible thing to see'

Video footage showed that Hamlin had been hit in the upper chest area.

American football, one of the most violent team sports, has been dealing with growing concerns in recent years over concussion injuries for players from hits to the head.

While injuries are common in the sport, multiple observers said it was the first time they had seen an ambulance enter the field to treat a player.

"I've never seen anything like that before," said former quarterback Kurt Warner on NFL Radio.

The NFL Players Association said "the only thing that matters at this moment is Damar's health and well being."

"The NFLPA and everyone in our community is praying for Damar Hamlin. We have been in touch with Bills and Bengals players, and with the NFL," the union said on Twitter.

"Please pray for our brother," tweeted Bills quarterback Josh Allen while players from across the league took to social media with similar messages.

Some fans traveled to the University of Cincinnati hospital where Hamlin was being treated, as did teammate Stefon Diggs.

Fans flooded to Hamlin's fundraising website, set up for a community toy drive, sending donations on his GoFundMe page, which had a target goal of $2,500, over $2 million after the injury.

The incident, broadcast during the weekly nationally televised Monday night game, drew reaction from athletes in other sports.

"The safety of players in all sports is always the most important," said NBA star LeBron James.

"It was a terrible thing to see and I wish nothing but the best for that kid. I am a huge fan of the NFL and football and you never want to see anything like that happen," he added.

The NFL did not give any indication of when the game might be continued or replayed.

Both the Bills and Bengals have already secured places in the NFL's playoffs, but the game was important for both teams as they sought to get the number-one seed in the AFC.

That would bring a bye and home-field advantage throughout the post-season.

The NFL regular season is scheduled to end on Sunday with the playoffs starting the following weekend.