Cincinnati, Ohio - Damar Hamlin has the entire American sports community rooting for him after the Buffalo Bills safety suffered an on-field cardiac arrest, as teammate Josh Allen pleaded: "Please pray for our brother."

Hamlin is still in critical condition at the University of Cincinnati Medical Center, where fans gathered to hold vigil after he collapsed during Monday's NFL game against the Cincinnati Bengals.

Hamlin made a tackle on Bengals receiver Tee Higgins in the first quarter, and after briefly returning to his feet, he slumped to the ground.

He was administered CPR on the field, before being loaded into a waiting ambulance and rushed away.

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Allen led the call for prayer for Hamlin, with well-wishers from across sports, entertainment, and politics also sending thoughts and best wishes.

Former Saints quarterback Drew Brees wrote on Twitter: "Damar Hamlin represents every one of us and every teammate we've ever had.

"I've never met him, but I know him as a member of our brotherhood. My family and I pray for him and his family as he recovers. God be with him."

Michael Vick and Patrick Mahomes also said they were praying for Hamlin, the latter adding: "Please be okay man."

Tennessee Titans quarterback Ryan Tannehill added: "Praying for Damar Hamlin, his family and everyone in Buffalo... no words for a situation like this," while Arizona Cardinals defensive end J.J. Watt said: "The game is not important. Damar Hamlin’s life is important. Please be ok. Please."

The tragedy echoed across different sports, with the NBA tweeting: "The entire NBA family's thoughts and prayers are with Damar Hamlin, his family and the NFL community."

That was reflected in post-game comments from a number of leading stars after Monday's NBA action, with Lakers star LeBron James saying: "My thoughts and super prayers goes up to the skies above for that kid's family, for him, for that brotherhood of the NFL and everybody a part of the NFL family."

James said it was "definitely the right call" to abandon the game for the night.

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He said of the incident: "It was a terrible thing to see and I wish nothing but the best for that kid, for the city of Buffalo, for the franchise of the Bills and like I said, for the rest of the NFL as well and also the Bengals that was there and playing in that game."

Klay Thompson of the Golden State Warriors added: "As athletes, sometimes the game can overshadow us as individuals or people."

"On behalf of the organization, we wish him the best. We're keeping him in our prayers and hoping for the best possible outcome. He's a tremendous person and it's bigger than the sport."

Amid the focus on Hamlin's plight, there was a surge in donations to a Christmas fundraiser the Bills star organized in 2020, to raise money to buy toys for children hit hard by the pandemic.

The fundraiser's target had been $2,500, but its running tally passed $3 million by the early hours of Tuesday.