Buffalo Bills safety Damar Hamlin is in critical condition after suffering a cardiac arrest on the field during an NFL game against the Cincinnati Bengals.

The emergency during the game on Monday night sparked an immediate outpouring of well-wishes from fans, commentators and other players,

and brought attention back to the dangers of the most popular sport in the country. The Buffalo Bills said Hamlin, who collapsed on the field after making a tackle, suffered a cardiac arrest.

The 24-year-old briefly got to his feet after making what appeared to be a routine tackle on the Bengals’ Tee Higgins in the first quarter but then fell on his back and remained motionless.

According to ESPN, medical personnel administered CPR to Hamlin and also gave him oxygen as they loaded him into an ambulance brought onto the field.

Players from both NFL teams, clearly shaken by what they had witnessed, gathered around Hamlin during the treatment, with many of them kneeling to pray and some crying.

“Tonight’s Buffalo Bills-Cincinnati Bengals game has been postponed after Buffalo Bills’ Damar Hamlin collapsed, NFL Commissioner Roger Goodell announced,” the NFL statement said in a statement.